cd-r playability

[tpcnksc]

hi folks--i have a brand new XP machine, roxio cd creator, music match burner, windows media payer/burner etc (pretty confusing actually--which one do you folks like?). i've downloaded mp3 files (entire albums with no track records...) from shareaza and burned them to a cd-r disk--it won't play on anything but my pioneer stereo cd player/burner--WON'T play in the car, not on my yamaha 5 cd player AND NOT EVEN ON MY new PC THAT BURNED THE THING IN THE FIRST PLACE?--what gives? what format am i supposed to convert the mp3's to (or is that presumabley automatic?)so that i can play the cd-r anywhere on my various cd players? i'm afraid i'll just be wasting cd-r after cd -r and never be able to re-record on them or play them on anything?

please help

ted