Good graphics card for Blu-ray on PC? And questions about HDMI & sound

Hey, everyone. I'm planning on having a desktop PC built for me later this month. I haven't talked to the guys at my local shop yet, so I'm not sure of the specs; all I know for sure is that I want to run Windows 7 64-bit and I want to watch Blu-ray movies on the computer. I'm not a gamer (I play a few online flash games, but that's it), so other than the Blu-ray, I'll just be using it for normal Internet stuff, watching downloaded or streaming video, editing photos, and listening to music. I know that I'm going to have the ASUS Xonar Essence STX sound card put in because I want excellent sound (I already bought very good 2.1 speakers to go with it -- this is a bedroom computer and any larger setup would be overkill).

So my question is about the video card. I've been reading up on them and it seems that people recommend the ATI Radeon HD cards over Nvidia cards for non-gamers who mostly just want to watch HD video. Is that accurate? There are so many models; which would be right for me? (I would prefer a card with a fan -- the case I want only has two 120mm fans and I worry about heat issues -- but one that will run fairly quietly.) And finally, many of the new ATI cards seem to have their own sound chips that drive audio through the HDMI. Would I have to get the sound from the video card? What would I do if I wanted sound from the ASUS sound card instead, and would there be any sync issues?

Sorry if these are dumb questions! I've never really researched this stuff before; I had my last couple of computers built for me by my local guys (and they were great and lasted many years), but I wasn't picky about what went inside them. This time I'd like to know as much as I can about how the parts work.