The Mac is known for its multimedia capabilities. But, one of the things I noticed when I got my first Mac (a Mac mini) back in 2005 was that it couldn't play the Windows Media audio and video files commonly used by many sites like NPR (National Public Radio). Microsoft had not pulled support for its Mac version of Windows Media Player yet. So, all was not lost. But, Microsoft soon after pulled that version out of production. Shortly after it licensed...

Flip4Mac

...to let Windows Media files play in QuickTime. I'm using it on an Intel-based MacBook (1st generation with a mere Core Duo :-).

There are also two for fee versions that provide other capabilities including exporting Windows Media files to another format.