first things first
What distro? - well It's personal choice. Personally, I would say that go for something that is newbie/desktop oriented, well, too start with anyway. My suggestion would be mandrake, because it's relatively "newb" friendly and there is lots of help both here at LQ or here
at mandrake users.
Also, for a relatively easy start, I would also suggest a genuine boxed set. If you have a reasonably fast connection, you could download it (3 disc's of about 650 megs a disc - hence the "fast" connection comment), there is also the "cheap disc" option, but this is only the download version that is copied and burned for you. Finally, the reason that I suggest the genuine boxed set is that there is some stuff on them that qualifies as commercial, but also some of the nuisance stuff is included and set up so you just do the install and ready to go e.g. the nvidia drivers.
SuSE don't offer the latest version for download, it's maybe 1 or 2 versions back - this is just their marketing policy, they would rather you pay for the most up to date version (fair enough I suppose).
Redhat is more of an "enterprise" type distro - I was reading something yesterday about that they are going to make it a more "desktop" type (well at least a version of it anyway). Mandrake is already more desktop (and originally based on redhat). Also, you can repartition with mandrake, even if you windows system is formatted as NTFS. You can't do that with a lot of distro's
Secondly, how much space?
Well, using the mandrake example, the ENTIRE 3 disc's is about 1.95 gigs so the 10 gig's suggested by ranger_nemo isn't far of the mark, that should give you plenty of "room to manoeuvre". Though it should be mentioned, that if you get really into linux, there are distro's about that are absolutely tiny and you could get away with a lot less space - it depends on what you install and run i.e. KDE is quite big (but IMO good) and uses a fair amount of resources (though not usually enough to cause a problem - judging by your spec).
Third, Hardware compatibility issues?
It's all well and good looking at compatibility lists, but the only thing that I use that actually appears on the mandrake hardware database is my soundcard (and even then, when I only had onboard sound facility, that didn't rate a mention). I have been lucky enough that the only problems that I have faced have been the AC97 audio controller (the onboard one), but I have had it configured, though it pissed me off enough to go out and spend about £50 ($70) on a soundblaster live! 5.1 digital. And the broadband modem that I had to start with, an alcatel speedtouch usb, which I also had configured (and it was a million times easier using the boxed set option, as most of the nuisance config stuff was having to use a download copy to start with), though I also changed that as well as there where a few things about the way it worked that pissed me off.
Fourth, OS learning ?
The learning curve is very steep. But I believe that in most cases this is because after someone has used windows for any length of time, you forget how "spoon fed" you have been with windows. Linux distro's on the face of it, dont do things in such a different way to windows, especially when dealing with how the applications look/feel/work.
Whereas, the actuall management of a linux system, IS very different to windows. Personally, I'm not all that interested in the actual "nuts and bolts" working of linux, I'm just a glorified desktop user and just "want it to work". Sometimes I struggle like hell with it, because I have to learn some of what's actually going on.
Again, have a look round the
and you should be able to find a list of what is actually included in the distro. There's certainly enough to make most things work.
I would say, that whatever distro you choose, take the time to read the links that fancypiper has posted. it's definitely a case of "read, read, read" (personally I hate trying to read and comprehend large and complex docs on screen. I would rather buy a decent book, but these seem to be in short supply i.e. most of the ones that I have looked at have been written for geeks, by geeks.)
So make some space and give it a go. as long as you still have windows disc's, it doesn't really matter if you screwed it up completely. You can still re-install, and the only thing that it has then cost you, is time.