Windows Security Essentials, Avast Free Edition, and Spyware Doctor w Antivirus (free). I also have MalwareBytes and SuperAntiSpyware that I run as occasional scans just to be safe (like once a month). I'm a technology professional and have never once had a virus on any PC I've owned, so while this is probably overkill, it's better safe than sorry, especially with all the development and things I do with my PC's!

AVG

Norton Internet Security (limited time subscription came with recently bought laptop)

Before that it was AVG (Gonna go back after the trial's done)

U Y NO Poll???

avira... though it's been a year, it might be time to review the competition again ^^

Avast no doubt for free anti-virus. You definitaly want Malwarebytes anti-malware too, Recommend both greatly.