windows media player does play avi's.

however i have a problem previewing movies. what you need to do is.
once you have downloaded enough to preview, exit limewire (make sure you exit through your taskbar aswell! if not then LW is just minimised) and the go to your incompletre folder. this is usually c:\documents and setting/ your name/ incomplete and double click on the file you want to preview.

if you dont exit limewire properly then when you try to preview it says file in use.

and dont worry when you restart limewire yoru downloads will continue where you left off!