I run the Spybot S&D and Ad-aware SE, along with McAfee AV. One thing to remember is, they all do different things, so they're all actually needed. Spybot takes care of spyware programs, Ad-aware works on pop-up programs, and the AV software watches out for viruses. Pretty much trouble-free, but once in a while, something might slip through here and there. My son tends to visit a lot of different sites, so I need to keep on top of it, and talk to him if I notice anything funny going on, due to something he downloaded.