Help, I can't get on Limewire and so now use Imesh but have problems with MP3 format.?

I recently have had trouble getting onto Limewire to download music for my ipod. So I came across Imesh instead but everytime I download any music, it comes up as WMA format which won't work with Itunes when I download onto my ipod. Does anyone know of any free music download sites that do MP3 format or how can I convert WMA to MP3 in itunes, cos I've tried converting it, but it says the WMA files are protected. This is driving me to distraction ! Help.