The latest worm to plague Windows users the Win32/Conflicker, also known as "Downadup" is spreading like wildfire. Sadly there's no excuse for people catching this junk and joining the bot-net. Microsoft patched this hole on October 23rd 2008 in a out of cycle security patch. So, people who have their updates turned on automatically are protected, those who don't can get Microsoft's updated version of their Malicious Software Removal Tool here, at http://www.microsoft.com/downloads/details.aspx?FamilyID=ad724ae0-e72d-4f54-9ab3-75b8eb148356&displaylang=en
I imagine most anti-virus programs will find this as well, but if your anti-virus is expired and your updates aren't turned on, you're probably hosed by now anyway.