Hmm... all the misguided attempts at getting better quality out of MP3 and such makes me really want to post a guide to getting high-quality audio.
Here's a link to an article describing the best lossy audio formats in some detail with further links to listening tests and likewise.
That said, I refuse to deal with any website that touts WMA as a viable audio format. It is not. WMA standard (which is what comes packaged with Windows Media Player) is a shoddy format that cannot come close to sounding like the original if you know what to listen for. Furthermore, it is proprietary and another one of Microsoft's attempts to abuse its monopoly power.
WMA is crap. That is all. 48kbps MP3 is worse. Try Ogg Vorbis or AAC if you want good low-bitrate audio.