Microsoft Anti Spyware is now Windows Defender

Microsoft renamed Microsoft Anti Spyware as Windows Defender and released the Beta 2 for the Windows users. It is free for download that helps Windows users to protect the computer against pop-ups, slow performance and security threats caused by spyware and other potentially unwanted software.

However, the Windows One Care also have the inbuilt spyware check. If you have OneCare installed, you need not user the Defender program. The look and feel of defender is almost same as One Care.

But, One care gives complete protection and maintenance like virus scanning, firewalls, tune ups, file backups, etc.

Defender link