My ibook reads audio cds but not dvds wha...

In order for a cd-rom drive to be able to read DVD's it had to be made to do that. Some older model CD_ROM's are not technologically able to read DVD's, You usually can tell if it can because it should have either a sticker or a raised portion on the front of the drive that says DVD Rom. If you have that then the next step is to install DVD playing software. Check both of those and then post back.