Malwarebytes Antimalware on demand SuperAntiSpyware portable on demand Spybot S&D with active Immunization and tea timer But ever sense I ditched the paid Kaspersky Internet Security for the free Comodo Internet Security, I haven't had any problems at all. Comodo stops everything, trojans, malware, & rootkits ect that just came out less than 24 hrs ago, I cant wait until Comodo 5 is released, it will include cloud & spyware scanning. Usually users infect themselves by using keygens, cracks & patches from warez sites, oh "but its only a false positive", lol this is what hackers feed inexperienced users who don't know any better!
For security I only use KIS 2011. I only use malwarebytes once per year, to check if everything is OK.