John's right about not running an anti-virus or spyware but to do that you need to change your behavior on the net. In lieu of that, I would look at the Microsoft One-care package. Its got the virus scanner and spyware programs that are fairly robust and still fairly lightweight.

Cost is not too bad. About the same as the other packages but for that you get a 3 machine license. There's a 30 or 90 day trial available at Microsoft's site.