thanks..i'm confused here tho...so it's better to get a 6000 or higher radeon for HD playback? because it said "The numbers suggest that the AMD Radeon HD 6670, HD 6570 and HD 6450 provide a high, yet not ideal, quality of DVD playback on a full-HD display."
It has to do with the way the scores are distributed based on whatever test has been performed. You will have to research what all those different tests if you want a true understanding of the scores if you do not accept that going with one of the higher score is always better.
As I stated getting the Radeon HD 5450 should be the lowest card you should buy, but the next higher card will have some algorithms to help improve video quality.
The ati 6000 series has a blu ray decoder built in, and the 5000 series and lowers uses CPU power for the decoding. An integrated ATI HD4200 series & up, Intel GMA X4500HD &up, and I think Nvidia needs a 9400m and up to handle HD video.