Windows Defender

If you don't have it installed yet you should consider it. I have been running the Anti Spyware beta from Microsoft for quite some time now, and today it automatically updated itself to Windows Defender Beta 2. This program has been quite helpful with protecting my kids' computers. The young ones doesn't always know what is harmful to their boxes or not. I've told them "if you see a big pupup with a spyware warning in the right corner - let me know at once" :)

About Windows Defender:

Windows Defender (Beta 2) is a free program that helps protect your computer against pop-ups, slow performance, and security threats caused by spyware and other unwanted software. It features Real-Time Protection, a monitoring system that recommends actions against spyware when it's detected, and a new streamlined interface that minimizes interruptions and helps you stay productive.