[DustyDan]

PAL, NTSC — the Mac won't care. It's the regions it cares about. It wants you to decide which part of the world you live in, but gives you those few changes in case you've relocated. The world is divided into all these separate regions for marketing purposes.

If your problem is that you have discs from other regions, then you likely will want to rip that disc so that it's region-free. (The PAL and NTSC part won't change.) To rip it region-free on the Mac, look at a program like Handbrake or Mac the Ripper.