Oh, if it's streaming video, then you're even MORE out of luck. You may be able to find some vague utility (or combination of utilities) that would let you convert a self-contained WMV into some other format, but if it's streaming video, then you're stuck using WMP to view that (or any other application that supports streaming WMV).
The problem is that the actual WMV data (the movie) is stored on the server, so the server itself would have to have the video encoded in a QuickTime-compatible format in order for you to be able to use QuickTime to view it.
Ain't gonna happen, sorry.