I install AVG Free on my customers machines when they come into the store with a virus/spyware infection. I never have any problems with it whatsoever. They just added the antispyware bit with this last major version. I haven't seen it in action yet, though. What I suggest doing is installing AVG Free, SuperAntiSpyware and Mawarebyte's AntiMalware. The latter two don't scan in real time so no resource hogging... I would generally only run it as you need to. Between those three apps, I'd say you're about 95% covered.