No longer able to connect to internet wirelessly
 

I need help connecting to the internet again. I have an HP laptop running Linux Hardy Heron & Vista Home Premium. I have a Linksys Wireless N router WRT150N and DSL internet.
First a little history behind what has happened. All wireless connections worked great until 3 days ago, when the download rate & browsing speed slowed down dramatically in both operating systems to 1-2Mbps...on the hard-wired desktop computer (Vista only) it is consistently at 100Mbps. I have no idea why this happened but after 2 days of it, I decided to try changing the settings in my router and the download rate shot up to 78Mbps. The browsing speed is also fast again.
Here are the changes I made to the router: I changed the Network Mode to Wireless N only from Mixed, changed the Radio Band to Wide-40MHz Channel from Auto, and changed the Wide Channel to 8 from 3. Now the wireless connection in Vista works great but I can't connect in Linux, even when I return the router to its original settings. It recognizes the network but won't connect.
Right now I am in Linux on my laptop, hard-wired to the router via a second ethernet cable and I can connect just fine, even with the new router settings, so something has gone wrong in the wireless setup. I may have messed something up when trying to figure all this out.
Does anyone have a solution for me?
I have read through a few of the threads and saw that you needed some additional info, so I did the lspci command in the terminal.Here are the results:

00:00.0 Host bridge: Intel Corporation Mobile PM965/GM965/GL960 Memory Controller Hub (rev 0c)
00:02.0 VGA compatible controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (rev 0c)
00:02.1 Display controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (rev 0c)
00:1a.0 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #4 (rev 03)
00:1a.1 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #5 (rev 03)
00:1a.7 USB Controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #2 (rev 03)
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 03)
00:1c.0 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 1 (rev 03)
00:1c.1 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 2 (rev 03)
00:1c.5 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 6 (rev 03)
00:1d.0 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #1 (rev 03)
00:1d.1 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #2 (rev 03)
00:1d.2 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #3 (rev 03)
00:1d.7 USB Controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #1 (rev 03)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev f3)
00:1f.0 ISA bridge: Intel Corporation 82801HEM (ICH8M) LPC Interface Controller (rev 03)
00:1f.1 IDE interface: Intel Corporation 82801HBM/HEM (ICH8M/ICH8M-E) IDE Controller (rev 03)
00:1f.2 SATA controller: Intel Corporation 82801HBM/HEM (ICH8M/ICH8M-E) SATA AHCI Controller (rev 03)
00:1f.3 SMBus: Intel Corporation 82801H (ICH8 Family) SMBus Controller (rev 03)
02:00.0 Network controller: Intel Corporation PRO/Wireless 4965 AG or AGN Network Connection (rev 61)
06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E PCI Express Fast Ethernet controller (rev 01)
07:09.0 FireWire (IEEE 1394): Ricoh Co Ltd R5C832 IEEE 1394 Controller (rev 05)
07:09.1 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 22)
07:09.2 System peripheral: Ricoh Co Ltd R5C843 MMC Host Controller (rev 12)
07:09.3 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host Adapter (rev 12)
07:09.4 System peripheral: Ricoh Co Ltd xD-Picture Card Controller (rev ff)

From your description, it sounds like someone in your neighborhood (perhaps even you) installed a new wireless device (fire alarm, intercom, etc.) that uses the same frequency band as your router uses, so the connection became unreliable and had to slow way down. (My daughter's baby monitor kills my wireless-g connection!)

Many Wireless-N routers have an option to seek among all the available channels for the least conjested one, and some will also use multiple channels to achieve the best throughput.

So:
First suggestion: Try to find out where the interference is originating and eliminate it.
Second suggestion: See if your modems have any adaptive settings and turn them on if they aren't on now.

If that were the case, wouldn't also affect Vista's ability to connect? I am wirelessly connected in Vista right now and everything is fine.
I have noticed that there are more wireless signals in my area of late, but we have not installed anything new in or around the house, so elimination would not be an option.
My modem is provided by my ISP so I don't think there is any way of changing its settings.
Thanks for your input though.

I suspect that your modem vendor has an arrangement with Microsoft, and, in return for MS support, driver certification, and automatic installation on Vista systems as needed, has allowed the Vista driver to change the modem settings as needed for optimum performance. (The methods for making such changes are often propitiatory, and need to be "reverse engineered" before they can be included in FOSS versions of the driver.)

So rather than admitting I'm wrong, I'd suggest seeing if, for example, ndiswrapper could be used to implement the Vista driver on your Linux system. (Or, make sure you've got the latest version of the driver you're currently using.)

I still suspect a new source of interference - not necessarily someone's wireless modem. As I mentioned, other devices can use the same part of the RF spectrum.

OK...I solved my own problem. You may think it a bit drastic but it worked! Here's what I did.
I backed up my Home folder to my external hard drive and re-installed Hardy Heron. I also reset my router to factory settings and re-entered the security information, and voila! Everything worked just fine, but the download rate and browsing speed was again really slow. I saved the settings for my router (I just learned that I could do that in my investigative efforts), and repeated the router changes indicated in my original post.
Again Linux could not connect wirelessly so I decided to see if changing one option at a time would make any difference. I noticed that I could change the Network Mode back to Mixed and still retain the changes to the Wireless-N settings. I restarted Linux and it connected perfectly with all the desired speed. So what I needed to do was change the Wireless-N settings and the channel, but retain the Mixed setting on the Network Mode.
I must have really screwed up something in Linux in my efforts to get the networking functional, so I decided that a clean install was the best option.
Just thought I would post this in case anyone else might be struggling with the same issues.