I found with viruses that they stop you getting to main antivirus websites, but they tend to forget that they make mirror sites for diff countries.
Go to
You must login or register to view this content. and download avg free(Yes it's free). It will not let you do the update when you install it as that's on the .com site, but if you install it and run it, it might find and delete the virus for you anyway. If it doesn't find anything I can get you the anti virus updates you require and then can try again.
Also download and install Spybot and run that deleting anything it wants you to. You might have to take of Windows Restore as copies of the virus can stay in there as well.
Let me know how you get on!
All this talk of reinstalling wont do anything unless you format the drive and then you've lost everything. Reinstalling without a format will just retain the virus.
Worst case scenario you're going to have to do a full format and a reinstall, but see how this goes for you.