Slow internet, possible virus?

I have had Vista since it went on sale and have never had any problems using
the internet before. But, a few days ago- seemingly out of the blue as there
had been no software or hardware changes to my setup- the internet on my
Vista desktop crept to a crawl. I use the Microsoft firewall and Avast. My
computer has a 4.1 rating and has had no problems related to the internet
before.

My XP laptop is fine on my wireless router and there has been no apparent
change in internet speed. It doesn't seem like it's a problem with my ISP or
router.

Things I've tried with no effect...
1. Plugging the modem directly into the desktop.
2. Complete scans with Windows defender, Avast, Ad Aware, and Spy Bot.
Removed low risk cookies, but that's it.
3. Copied files over to another drive and backed them up on DVD, then
reinstalled Vista. IE was slow when I tested it and I haven't bothered
getting Firefox yet.

What's your guys' take? Shouldn't the reinstall have wiped out any virus or
malware?

Thanks for the help!

Hi Mr. Cool,

You might try this and see if it is a TCP/IP Auto Tuning issue:

Auto Tuning - TCP/IP receive level

Hope this helps,
Shawn

Thanks for the response, Shawn.

I tried what was suggested on that page, but it didn't have any effect. I
might try reformatting my secondary drive and then doing the reinstall again.

Sorry it didn't work. I hope someone can come up with a solution for you. I do not know what else to try.

Shawn