When moving music files from i tunes to MP3 player what format should i use? ex: WAV, xml, txt, etc..?

It depends on what formats your player supports. If your files are in MP3 format, then pretty much any player on the market will be able to play them. If you are using an iPod, then AAC format, the iTunes proprietary format, will also work just fine. But if you don't want to worry about any conversion at all, then MP# format is your best bet.