Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
can i play .mkv's??? or avi's?

No

http://www.apple.com/appletv/specs.html


Video formats supported
  • H.264 and protected H.264 (from iTunes Store): Up to 5 Mbps, Progressive Main Profile (CAVLC) with AAC-LC audio up to 160 Kbps (maximum resolution: 1280 by 720 pixels at 24 fps, 960 by 540 pixels at 30 fps) in .m4v, .mp4, and .mov file formats
  • iTunes Store purchased video: 320 by 240 pixels, 640 by 480 pixels, 720 by 480 pixels (anamorphic), or high-definition 720p
  • MPEG-4: Up to 3 Mbps, Simple Profile with AAC-LC audio up to 160 Kbps (maximum resolution: 720 by 432 pixels at 30 fps) in .m4v, .mp4, and .mov file formats
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.