Check that the program's not trying to burn to a CDRW, as these are formatted differently and will only hold about 500Mb. Don't know if you saw my edit earlier on, but check whether you've got 477Kb or 477Mb left. With 696Mb used, you should have about 477Kb left. Any other probs Pete PM me and I'll try and put you straight.
Rob, that figure I gave for CD quality is what Media Player use to say, but I bow to your superior knowledge mate. I normally use Nero and have done for donkey's, wouldn't normally touch MP with a barge pole.