I've been installing Avast on friends and family pc's for years. I keep toying with AVG because I figure it's popularity is no accident but I always return to Avast. A broad coverage of services by it's on-access protection and it's light system footprint makes it an easy choice over Symantec, Mcafee, etc.. I wish they had a viable Enterprise version.

I only recently started using MBAM. It immediately shot to the top of my list. Between MBAM and Spybot, you really don't need any other scanner/removal software (AdAware Anniv. Edition is just cr*p). Throw in SpywareBlaster and Windows Defender (and a little user training) for preventive measures and most of the systems I work on never require major cleaning.