If you're not using Windows Defender, you probably should be, anyway it's noe left beta and is still free and includes two free support incidents, 99% of us will never need support so that's cool.

http://www.microsoft.com/athome/security/spyware/software/default.mspx

I had to uninstall the beta because it has some .dll's missig and it kicked up a fuss every time I tryed to install COD2, Hopfully this will fix it, as it caught the virus I got a few months ago before AVG (one of the reasons I no longer use AVG)