MP3 or WMA FORMAT?

[Soleron]

Use MP3. It's still patent-encumbered, but less so than WMA or AAC. The quality difference between them is negligible.

Of course, I'd rather everyone used OGG Vorbis. It's smaller, better quality and requires no licensing. I can't play any MP3, WMA or OGG files on my (Linux) PC without breaking the law.