What version of OS X do you have? You can check by going to the Apple menu on the upper-left hand side and clicking on About this Mac.
If you have 10.3.9 or above, you can download the
Flip4Mac codec which will allow you to play WMV files in Quicktime Player.
If you have any version below that, you can download Microsoft's
Windows Media Player.
Keep in mind that the latter is an outdated version which will only play WMV9 files. Flip4Mac does not have this limitation.
.rmm files are Real Media files, which requires
RealPlayer. This also requires 10.3.9 or above.
edit: hmm, WildCowboy beat me to it.
irmongoose