Packet Switched Press unboxed their Xbox 360, put it through its paces, and wrote all about it.

In particular, they mentioned a couple thing you might find interesting:

My Videos: All our personal Windows Media files streamed flawlessly, but the bigger things to point out are these two…

• DivX and Xvid did NOT play
• 720p High Def Windows Media video (Friday Night Lights and Robots, downloaded from WMVHD.com) DID PLAY, and looked spectacular. The close-up of the robot below is actually only a small part of the full picture. Trust us, it looked very good (at least progressive scan DVD quality, if not better). This was perhaps the most pleasant surprise of the entire evening.

They have plenty of screenshots, so check it out.

Packet Switched Press - REVIEW: XBOX 360, media-centric features