Haha, I know this is late, but if you ever want to watch those kind of files [wmv, asf, etc] or any other common files that don't seem to be playing on your mac, you can dl Windows Media Player for the Mac from microsoft, and also Mplayer for OSX which seems to recognize every file type I've thrown at it. The address is:
http://mplayerosx.sourceforge.net/
Enjoy your mac. What kind was it btw?