Be very affraid when using wma files. You may find that you get locked out of files that you converted from CDs that you own.
Microsoft Wma files and copy protection is bad for consumers. If you can, then avoid them like the plague.
ALL Mp3 players will play your Mp3s. But few play wma files. Drive space is cheap now days. And wma files sound worse than mp3 files (based upon the fact that every wma file that I have heard sounds like crap).
But if you still wonder, then convert some over to wma for yourself.