Anti Virus Software

[Darren B]

NOD32 is my choice, very low impact on performance http://www.eset.com/
great for home and business use, various update methods for lans

[pnagames]

Kaspersky as it is a beauty out of the box

just remember to leave the updates ont he automatic and not download their beta updates / patches

[gabrielcrowe]

NOD32 smart suite

I wholeheartedly agree. This is by far the best of the bunch.