You don't need to "rip" audio CD tracks to make a compilation as it can easily be done by using Nero in the tracks' original form.
You will have to keep copying whichever tracks you want in the compilation from each CD (inserting and removing each CD) until the disk is almost full; the bar at the bottom of the compilation menu advises the space remaining.
Remember that a CD plays from the inside out so if you want a particular tracks order you will have to work "back to front" when compiling the list i.e. last track first and so on.
An explanation of the method is readily available either in the Nero Help files or from the click here website.