.mov?
but yea heres how you can do it. since one is for mac and one is for pc theres quite a process. i believe this is the only way to do it:
load your wmv video into movie maker, then save to my computer as .avi. then load the .avi movie up into adobe premiere. then put it in the timeline then go export>adobe media encoder. then when it brigns up the window, for format, select quicktime. there will be a severe quality loss because premiere is based on pc and your making a quicktime out of it.