Microsoft on Monday shifted Windows Defender from beta to final, and added limited free phone support to the no-cost anti-spyware software.

Defender -- which launched as Windows AntiSpyware almost two years ago after Microsoft acquired New York-based GIANT Company Software in 2004 -- had been most recently pegged as Beta 2. According to Microsoft, changes in the final include additional scanning performance improvements, support for the 64-bit edition of Windows XP, and automated spyware cleaning during scheduled scans.

Microsoft also announced free phone support for Defender, but limited the support to two calls per user.

At the same time, the Redmond, Wash. developer dropped support for Windows 2000, citing the aging operating system's business audience and Defender's target of consumers. "We decided to focus more on Windows XP and Windows Server 2003. Both of these operating systems with the latest service packs have significantly better security protection overall, which will also help to prevent spyware on those computers that run those operating systems," Microsoft said in an online FAQ.

The final version of Defender can be downloaded for Windows XP and Windows Server 2003 from here. A separate edition has been integrated with Windows Vista, and will be bundled with that OS when it hits retail next year.