I'll be honest, no Anti-Virus software even keeps you 90% safe anymore. There's new viruses created every what, 10 seconds or something crazy. But personally, I use Webroot as it not only updates every 2-3 days, but it also deletes processes in the Task Manager that are or could be dangerous (Keyloggers, Botnets, etc). (33 processes running after the sweep. 60 before the sweep).
I'm not sure if it's the specific type of Webroot anti-virus that I bought, but that's a lot to ask for in any program.