Im not that new to mac but been awhile, Had a macbook untill the ipad came out and sold it for a ipad. But now its time to leave the windows desktop back to mac, deciding to go with a new Imac 21inch I5. But on this current windows machine I have alot of .mkv / .xivd etc movies. But I also intend on getting a new appleTV to start using airplay my 1080P videos. But what format is ineeded in Itunes to be able to do that? I have around 150 Videos that need to be converted but I dont get my Imac for about a week so im starting now. I have Xilisoft Video Converter Ultimate witch I intend to buy the mac verion too.