Your music files must be compressed or low quality MP3's. I have never put that many on a single CD, so I can't say if itunes can handle that or not. If you have the better sound system in your car, you might consider a larger or higher quality MP3. Of course, you will not be able to fit as many on your CD as before. You can adjust the preferences in itunes so that when you rip your original music CDs, you can select which level of quality you want. This will affect file size. If you purchase songs from itunes, you can either do one of two things. You can either use the protected ACC format or you can convert it to a nonprotected MP3. Either way, it will play. For your other MP3's you have, you will have to import them into itunes. You should be able to find that command, then navigate through the dialogue boxes to select your files. In itunes, you just create a playlist with the songs you want, then burn it. At some point, it will tell you if it won't fit on a CD. You may be able to figure out from the size of the playlist if it will fit or not before you try to burn. There are lots of tips and info on the apple web site. Good luck.