You guys have it a bit confused...
PAL = A video format.
Region = A code put on commercial DVDs indicating the region it can be played in.
Your computer could care less if the video format is PAL or NTSC. It will play both happily forever.
Your superdrive can only change regions a set number of times. But not all PAL disks are a different region, and not all different region disks are PAL (Japan, for instance).
If you have a PAL disk of a different region, your best bet for long-term use is to burn a copy of it in a computer with a region-free drive (some older superdrives can be patched to be region free, and many commercial DVD-R drives can be patched this way too), and have the burning process remove the region encoding to make a 'region-less' disk for you to use. This is legal, since its your DVD. This PAL, region-less disk will play happily in your computer without having to reset your computer's region.
peace,
sam