I had the same issues as Phreaker22. The Antivirus 2008 virus I think is created by a Virus called smitfraud-C - or at least that virus was present at the same time as all the Hijack activity going on for Antivirus 2008.
The virus was relatively easy to clean up with Panda Antivirus, ExterminateIT and Spybot S&D - but it has left my (genuine) copy of Windows XP Pro with the message "Unable to complete Genuine Windows Validation"
I think the suggestions by MS staff to reinstall Windows are just ridiculous - my computer is completely free of virus now as proven by any number of scanners.
A reinstall could take many days work to get all the drivers, games and files reinstalled.
Unfortunately I can't run a Windows repair (as suggested by MS forum) as my installed system has upgrade to SP3 and my media has only got sp2 on it - so the Windows repair process won't let me continue.
Microsoft needs to lift their game here - virus and Adware are unfortunately a fact of life - look at the number of posts on this forum from people who have failing WGA due to virus issues.
Just saying "reload windows" seems somewhat arcane - surely MS can device a way of just getting through this.
I am just going to live with the message as the alternave is too horrendous to consider - which I don't think was what MS wanted when they introduced WGA?
Respectfully,
Murray