I don't agree with using 2 AV programs - they all hook the file system, and you can get some really weird interactions. One of the worst computer messes I ever cleaned up without re-installing windows involved _6_ AV programs - and a virus.

I know I'm coming across as a Norton fangirl, but it works. And the performance today is amazing compared to where it was 5 years ago. It really doesn't bog down a machine any more - especially not in comparison to running 2 free AV programs!