That is a gaming card. The most powerful and expensive one in existence. If you want a card for home theater use that is definitely not what you should be looking it.
A good high end HTPC card would be the HD5670.
If you want the best picture quality then look at getting a HDTV with very good to excellent picture reviews / ratings. For the purposes of watching movies a HD 5970 will not be any different than a HD 5570.
Yeah, like I said, the max you should be considering is the HD5670, the HD5570 will do nicely as well. You will gain nothing other than a lighter wallet and a higher power bill by buying a card more powerful than those, much less something crazy expensive the HD5970.