Microsoft just released Windows Defender to the web. Check the Windows Defender home page for download links and additional information. Aside from some basic UI changes, the big news is that Windows 2000 is no longer supported. The FAQ says this change is due to Windows 2000 being outside mainstream support. However, given that the previous release worked just fine on Windows 2000 (and not much appears to have changed since then) we are left to guess that marketing trumped the product group on this decision.
Note: Make sure to upgrade to the final release sometime before December 31, 2006 (official end-of-life for Defender Beta 2).
Check out the WindowsConnected Windows Defender RTM photo gallery for screen shots of the install & first-run experience.
Enjoy - and let me know what you think about the Windows 2000 decision. Thanks.