Antivirus

Microsoft Security Essentials

Still like AVG here.

Still like AVAST and been using it for years.

+1 from me, don't think I'll ever use anything else again. I used to have the full paid-for version of Trend Micro, and MSE has really impressed me.

i second that one, its not free but its a awesome deal, $59 for 3 PCs for a year.
$19.66 a year per PC.
or get 2 friends to go in on it and there ya go, very cheap but Very good AV

http://www.microsoft.com/security_essentials/

Like grumpy said use this with the pc tools firewall plus!