Windows 7 internet connection is suddenly very slow

++Fixed, see final post

I've been using Win7 for about 2 months now, and all has been going well until 2 nights ago. I noticed that my browsing speeds were very slow, so I just assumed it was my network, and went on about my business. Tonight I fired it up, and ran into the same thing.

I rank the Speakeasy speed test, and my download speeds were only at 300kbps on a 5mpbs line. I started doing some checking on my router, modem etc. and then I had the brilliant idea to run the same test on my laptop running Vista. No problems there, got a full 5.2mbps download. So, I think that rules out anything with my ISP, modem, router etc.

I've uninstalled and reinstalled my wireless network device drivers, changed my auto tuning settings at the command line, turned off the firewall on my pc, closed all unnecessary processes (there's not much on here, fairly fresh install), restarted, held my breath, tweaked settings on my network card, but nothing seems to be improving. This is consistent across Chrome and IE8.

I've been reading through other posts about the same sort of issue, but I haven't come across anything that works. I don't have any AV software installed (I like to live on the edge) but I did run a spyware scan and it came up clean.

Any other ideas? I run a small website business out of my house, and it makes times pretty tough when it takes forever to connect to anything, and then to upload any files. I've wasted an entire evening trying to come up with a solution. Any help is appreciated.

This may help

Why is my Internet connection so slow?