Argh! My Internet has become so slow!

Hey all - So my main system is an old but reliable home built P4 3.0 ghz running WinXP Home, 2 GB RAM, 500 GB HD, connected to a Comcast cable modem (connected via ethernet cable through a linksys router). While fairly old, my system works fine for basic Internet usage and has been humming along until about a week ago when it inexplicably became very slow to load Internet pages. Whatever browser I've tried (Firefox, Chrome, IE8, Opera), it takes a good 30 seconds-1 minute for a page to load that just last week would have loaded in a couple of seconds. I haven't installed any new apps or made any other configuration changes.

My Internet connection doesn't seem to be the culprit as it's fast as ever on my laptop, and I have done virus scans (using AVG8, which is installed on my system as well as trendmicro's housecall), adware scans, run registry cleaners, defragged my HD, tried the ipconfig /flushdns then /renew trick, etc and nothing has worked. I tried disabling my firewall (Comodo Pro 3) and it made no difference. Any suggestions? I am pretty close to spending Saturday reformatting and reinstalling! Thanks.

 

It might be the computer itself or the services running on the computer are using most of the virtual memory.