Well I got to spend a wondourous 12 hours removing an infestion of the "Vista Anti-Virus Security 2011" mal-ware from my son's computer.
While the computer was running AVG Anti-Virus software, I never got around to upgrading to the AVG Internet Security Suite. Nor had I installed Spybot Search and Destroy and MalwareByte Anti-Malware programs. The infestation basically rendered his computer's Internet Explorer and Firefox browsers inoperable because as soon as they would start up the "Vista Anti-Virus Security 2011" mal-ware program pops up warning of that "Vista Anti-virus Firewall Alert - Vista Anti-virus has blocked a program from accessing the internet Internet Explorer is infected with Trojan-BNK.Win32.Keylogger.gen Private data can be stolen by third parties, including credit card details and passwords".
Anyway, after getting the system rebooted in "Safe Mode with Networking" I was able to get the above programs loaded and the system scanned multiple times with all the spyware and malware infections removed his system re-booted and is working like a new machine.
If you run an Anti-virus program only, your system is still at serious risk. I normally run AVG Internet Suite along with Spybot Search and Destroy and MalwareByte's Anti-Malware programs. These three programs pretty much keep all of the computers that I am responsible for maintaining (about 2 dozen at work, home, family and friends) running without incident. When there is an incident it is usually because for one reason or another one of these products was disabled or turned off.