You wouldn't believe there are still companies out there that are so windows centric, that it isn't even funny anymore. Take XM radio. Top of the technology curve you would think. No way. They only support windows explorer and claim netscape (but oddly enough both mozilla and firefox do not work) and aol. Forget Mac (even safari) and Linux, you cannot sign up. sirius on the other hand doesn't seem to have a problem signing you up with other browsers.
Listening online? Forget that too. Only windows media player for now. No support for RealAudio. For the moment Mac can still use an older (V9) version of Windows Media PLayer, but you may wonder for how long that still works as Microsoft doesn't appear to be too interested in supporting Mac. What a wonderful web world.