Saw this at Windows Media Technology download page, dated 24 Septmeber.

Get fast and flexible playback with the best audio and video quality for Windows and the Web. Includes special new features optimized for Windows XP. Read more about the updated build 2800 in the release notes.

At a glance this release fixes the following: Addresses reported issues related to personal firewalls and surround sound speaker settings Download Windows Media Player 9 Series Beta (Windows XP) - Updated Build 2800