A free tool for Windows systems

I found another tool for windows systems , I have windows XP and have used it for a week and it seems to do what it says. Abtrusion Protector™ protects your computer by keeping track of all the executable files (applications, OCX controls, dynamic link libraries, drivers etc.) that are installed on your computer. Whenever the operating system tries to load a piece of software, Abtrusion Protector™ first verifies that the file is allowed. If the file is not recognized or is not allowed to run, Abtrusion Protector™ prevents the operating system from loading it.
It is free and worth a try.

http://www.abtrusion.com/