A relative of mine uses Net Zero dial-up and is also constantly getting her computer infected with malware. Maybe clicking on bad links, maybe not keeping a/v and security updates updated and getting infected with drive-by malware.

I'm thinking of getting her set up with the easiest version of Linux possible that does what she needs. Search for information on the web, shop on eBay, read e-mail online, look at photos people send her as attachments or links and maybe look at an occasional Youtube video link someone might send her in an e-mail.
She also needs to be able print with a supported printer that will "just work" plug and play when it is plugged into the computer's USB port. No manual downloading drivers or configuring.

She cannot afford even $30 per month for the cheapest DSL broadband, so she currently pays about $10 per month for 56K Netzero dial-up.

I'm thinking about setting up my no longer used 2008 Centrino laptop with either Mint or Peppermint OS and getting her a Walmart pre-paid broadband Mifi with the $45 for 1GB plan. $45 for 1GB is not cheap, but this plan doesn't expire, so she could make it last at least 3 or 4 months and that would end up being cheap. She does not stream music or video or download music or video, so bandwidth use should be pretty light each month.
This MIFI will use Spring 3G as the connection, so it will not be fast, but will probably still be noticably faster than 56K dial-up.
To avoid malware, I thought of setting it up as a Live CD so it will be impossible to get malware and her limited bandwidth will not be wasted downloading software updates every few days or weeks.
The problem with the Live CD is that she would have to set up the wireless on every reboot and I wonder if constant use of the CD would wear out the CD drive.
If the OS is installed on the local disk, it will run better and save her settings on reboot, but she still will have some chance of getting infected especially if software updates where disabled to avoid using up her bandwidth.
Linux is targeted with much less malware than Windows, but I wonder if she might still manage to get infected with whatever malware is out there for Linux like a spam trojan that will waste her bandwidth sending spam from her PC without her even noticing if the Live CD method is not used.

Any thoughts, suggestions and opinions on the best set up for this scenario?

If she could restrict her use to Netzero DSL then she could use almost any distro.

The only way I ever got netzero dial up to work is with an internet connection sharing on a windows system. You may have to check that now as it might have changed.

A custom live cd might work. Might be able to use a custom or stock live usb. DOD offers a pretty good usb image.

The plan is to give up trying to use NetZero dial-up if she switches to Linux.
That's why we are looking at the Walmart broadband plan as an alternative.

http://www.walmart.com/ip/TruConnect...ndingMethod=rr

It could be plugged into a power outlet and used as he home Internet connection and maybe she might take it on the road with the laptop once in a while.

Since she doesn't do video or audio streaming or downloads, 1 GB could last at least a few months on this plan. This is the only plan I have seen where the data allowance doesn't expire monthly.
They also have 500MB for $25 if she is really tight on money. She can get 1GB for $20 on another plan that uses a Virgin Mobile Mifi instead of the Sprint Mifi, http://www.walmart.com/ip/Virgin-Bro...ivery/15443368 but that expires monthly, so $20 per month is the the minimum she would have to pay every month.
There is also another service that uses T-mobile 4G for a good price $35 for 3.5 GB of data that expires after 60 days. http://www.walmart.com/ip/T-Mobile-3...ndingMethod=rr (works out to about $17.50 per month plus taxes).
The advantage is that it is faster than the others and is more data, but the disadvantage is that it expires in 60 days and you are limited to only 4G (no 3G fail over) and T-Mobile 4G has a much smaller coverage area than 3G. I'm not sure her house is inside the 4G T-mobile map area. So, the slow Sprint service will probably be best for her.

Several distros still provide dial-up support, ready to use. The easiest and lightest of these are AntiX, Bodhi, Swift, and Vector.

I wouldn't worry about a trojan. It's got to be written to run under a specific OS, and few spammers are going to bother to write one specifically for Linux. How many people here have ever reported being affected by such a thing? None, that I can remember.

Be aware of updates. OOo updates under older Ubuntus was basically a new install; 120MB down the drain. OK, they don't come often, but it's something to keep an eye on.
Another 'problem' might be large attachments in emails by people who don't know how to properly resize photos or whatever they attach.

For a long time, I had a 1GB cap. My provider did (does) send a daily report so I could keep an eye on it.

I would say Debian Stable and all software DVDs: http://cdimage.debian.org/debian-cd/...amd64/iso-dvd/. This would allow software installation offline, and as a Stable release, it'd not need to be updated often (not at all, if you just use the DVD's for software).

since she's new to linux, use either mint or ubuntu otherwise she might find it hard to use linux.

You didn't mention hardware for her computer. If you are thinking about Mint, check there minimum hardware requirements for starters.

This is what I meant. http://www.netzero.net/dsl since you'd need a modem, I'd make a huge assumption that it would work on linux.

Netzero DSL is not available at her address. That's why she pays for dial-up. Netzero dial-up uses some kind of proprietary dialing software for Windows and if there is a way to hack it to make it work with Linux, I'm sure it would be too difficult for her to use.
It will be an older laptop that had XP on it when it was new. Peppermint works on it.
After reading more about live CDs, I see they are not safe for regular use. I found that either they have blank Root passwords or some well known default Root password and they are missing security patches. It will be easy to get hacked during a live CD session if you end up on the wrong website following links in e-mail and Google search results that a non tech-savvy person will easily fall for.
The only security advantage to live CD use is that when you power off, everything is wiped out (except whatever malicious code may have been written to your disk drive the malware mounted it and wrote to it). During the session, you can still get credentials stolen when you log into email or banking sites if some trojan gets installed in memory. The password info gets sent out to some remote site, so it doesn't matter if the malware is wiped away when you turn off the PC. The damage was already done.

Because of this, I think we will install Linux on the disk drive and have it do automatic security updates. (Get antivirus too?) The OS updates file sizes don't seem like they are large if you don't upgrade to whole new versions so it should not use that much bandwidth. I tested installing Peppermint from CD and the updates downloaded after the install were only about 55MB total.

I will get her either a Virgin Mobile or T-Mobile prepaid hotspot she can use to replace Netzero and suggest she take the laptop to Starbucks or McDonalds if she wants to watch more than a couple minutes of online video so she doesn't have to worry about using up the allotted bandwidth before the monthly period ends.
She should be able to get by with 500MB-1GB per month mobile broadband as her sole home internet if she just surfs the web, uses e-mail and doesn't watch videos. She couldn't watch video before anyway because her PC was even older than this laptop and it was bogged down with constant adware popups and spyware stealing resources and it was on a super slow-dial-up.

If all else fails, consider a clean install from OEM disks back to xp. Install all updates and get a good security suite. At least MS security essentials. Use other tools to limit issues like make a limited user account for her to use always. Create a strong admin password. I still like hosts files if for only the speed issue of blocking ad's.

Fedora is no an option? presto reduces dramatically the size of updates; it has Gnome 3, simple and user-friendly UI; AdBlockPlus helps to reduce bandwidth usage

http://fedoraproject.org/

http://adblockplus.org/

That's something to think about, but it really has to be dead simple. This person can barely turn on and off the computer and get around the Windows desktop much less configure anything in Linux.

If it is too confusing for her, the last alternative will be a used iPad 1 with 3G built in. I'm not sure she is willing to pay $25 per month for 2GB of AT&T 3G bandwidth, but she might. There next smallest plan is only 200MB per month. She would also be able take it to an Apple store and have a Genius help her with problems and, with 3G built-in, she won't have to added complexity of dealing with a MiFi.
An iPad 1 with just Safari and maybe the eBay app and a printer app or Airprint compatible printer might be the best thing if she can deal with the touch screen.

This might get blasted by some, but if it were me I'd use Slackware. My reasoning here is very simple.

Slackware comes as a complete distribution, for the needs she has a browser is about all she needs and an HP printer is usually just plug and play because of HPLIP. In other words the software is there from the beginning.

Secondly, because of the way software is added to Slackware you won't have to worry about her installing something that screws things up.

Thirdly Slackware is VERY stable.

I've done the same thing for my kids when they were 4 and 6 and by setting up a standard user account I had no worries about them screwing anything up. The biggest fix I had to do was to reset the DE to default configs a few times, but in your case you could even go so far as add something like to rc.local so that it automatically resets the default desktop at every reboot.

If wifi is available is there not DSL from the local telco? I don't know prices where you are at but $19 a month will get you 768k dsl from all the telcos in the dallas area, even in the rural areas, unless DSL simply isn't available, but even in very rural areas those places are becoming smaller.