FWIW, WMA is only a container, and can contain an audio stream or streams encoded with just about any audio codec. Something that merely says it supports WMA is of very little use since the odds of it having the codec you need once it cracks open the WMA file isn't very good.
So if you already have software to crack open the WMA, you next need to figure out what codec the audio files you have were encoded with. Then install that codec, and the WMA player you are using will probably work.
I use Flip4Mac personally for WMA/WMV files. It also installs most of the audio codecs you're likely to need.