<< i tried ati's player on someone elses PC, and it was darker, and not as clear as the powerDVD player >>
I use both ATI DVD 5.0 and Power DVD 4.0. IMHO, they have similar IQ and CPU utilization. If it were a choice between just using the ATI player, and Buying and using PowerDVD 4. I'd just use ATI DVD.
The point is, you want to make sure you use a player that utilizes the DVD assist, be it WinDVD 2.0, ATI DVD 5.0 or Power DVD 4.0. That brings the CPU requirement down to 266 mhz for smooth playback.