Why would I watch DVD's on a computer ? I wouldn't, I watch DVD's on my DVD player with 700 Watts of surround sound. However that is a bit impractical in my son's bedroom. A computer on the other hand that serves as an educational instrument, a CD player and a DVD player is a different and desirable situation.
My RiscPC has served me well and its very reliable. My son's PC is a pain in the butt when it goes wrong. But I've reached that point where I have to compare basic 21st computer functionality vs reliability. I suspect (I will find out) that an Apple is far more reliable than a windows PC and thus a good replacement for my trusty reliable RiscPC. Functionally there is no comparison. Ten years ago there was a comparison. Mind you 10 years ago and the awful windows 95 had just replaced the absolutely abysmal windows 3.1 and the Apple Mac was clunky at best.