Windows Defender
Microsoft used to have a beta version of Microsoft Antispyware that worked quite well. When I moved to Windows x64, I stopped using it because it wasn’t compatible. Now Microsoft has released Windows Defender, essentially beta 2 of the antispyware software.
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.
I don’t really need to use antispyware software but a lot of people I know need to. So you should probably upgrade to this latest version. It updates itself automatically, can run nightly scans, etc, etc. Just make sure you have a legal version of Windows as this can only be downloaded after you’ve passed the Genuine Advantage test.