Microsoft Malicious Software Removal Tool
Microsoft makes a pretty good malware removal tool called the Microsoft Software Removal Tool. It runs a quick scan of your computer upon reboot after each security update. But, you can run the scan anytime you want, and run a much more thorough scan. Running the in depth scan each month in addition to your other scans adds one more level of protection.
The file is called MRT.exe and is located in the c:\Windows\system32 folder. Just find the file in explorer, right click and select copy, then go to your desktop and right click and select "paste shortcut". You can then drag this shortcut into your monthly Maintenance Folder.
The program also maintains a log file called mrt.log in c:\Windows\debug which you can peruse with a text editor.
Dated: March 2009