Hardcore antivirus needed...

Well, my computer is now a cesspool of viruses. It's nothing really critical. It turns off and reboots as normal. But whenever I get home after leaving it on all day, I'm treated to about 87 pop-ups. Nothing works. What are some good, possibly free/trial antivirus/antispyware programs I can use to eliminate (or at least lessen) the infestation?

Reformat.

- install firewall prog. or turn on built in xp firewall if your 
  on xp

-if get latest windows updates.

- Firefox for web browsing (use ie only for win. updates)
http://www.mozilla.com/en-US/firefox/

- AVG Free anti virus
http://free.grisoft.com/doc/2/lng/us/tpl/v5

-ad aware (spyware check/clean)
http://www.download.com/3000-2144-10045910.html

-spybot search and destroy (spyware check/clean)
http://www.safer-networking.org/en/download/index.html

- spywareblaster (spyware blocker)
http://www.javacoolsoftware.com/downloads.html

xp tweaks/security I would recomend
Steps.
4,5,6,12,13

complete spyware/popup rescue kit

AVG (as above) - antivirus

Lavasoft Ad-aware (also as above) - antispyware

BHODemon - some stubborn programs require this for removal, believe it or not a installed Browser Helper Object can register itself to startup with explorer.exe

ProcessExplorerNT (from Sysinternals) - kicks task manager's ass, can tell you what programs are starting the svchost.exe's

Autoruns (from Sysinternals) - control what programs run on startup and discover where they are at

Firefox 2 and StartupMonitor - so this shit won't happen to you again!

>>4

Don't forget Hijackthis