Plenty of software will burn mp3s to CD - I use CDBurnerXP, look in the "free software" link in the FAQ sticky. I seem to remember that MS Media Player will do it too, although it's a year or two since I last used it.
However, you'll never get CD quality back from an mp3 - you have to throw information away when you compress CD audio to mp3, and once it's gone there's no way back.