Also, some newer video cards have decoding built in. I have a 12x DVD (Afreey), a P3 866 and a GeForce 2 MX 64 meg, and I have no problem whatsoever.
Minimum requirements for trouble-free viewing are probably a 8x DVD, and then either a 600+ processor (for software decoding), or a decoder card or good video card that supports it.
Apple? Macintosh? What are these strange words you speak?