PS3 is more powerful on paper.
Every multi format game to date looks better on the 360 except one, oblivion. This is due to the texture update to the game. (oblivion was out on pc and 360 before the ps3 was even released)
The True reason behind 360's advantages over the PS3 is
1: Time, yes it has been out longer therefore game developers know how use the hardware better
2: 360 is far far easier to program for, more user friendly which equals more better looking games (it would be great if companys made games for the sheer joy of making them but the facts are if it cost you more money to make the same game for 360 look better on PS3 aswell as an extra 5 months work are you going to make any more money?? No you won't, i will also add this is one of the reasons that GTA is running late as both formats have to be realeist at the same time and it take so much longer to get a game to run smooth and good looking on the ps3)
3: Although on paper 360 is less powerful on paper, the far simpler design means it makes better use of its power, less waste and generally more efficient, think of the 360 as a lower powered pc than the PS3 but over clocked, or a crappy car with NO2.
In terms of dvd/HD/media player i have no idea, im new to the whole home cinema thing although im trying to learn it all but what you have to rember is the 360 with hd add on isn't as good as a hd player. The PS3 isnt as good as a standalone Blue ray player.
If you want to play games go for the one you will play more, not the one that offers X= FPS or or 7.1 sound. Go for the one that offers you the most games that you want to play, not the one with more out.
Hope this helps