I have to say, I hate using my old skool Xbox 360 for anything, unless we're having a loud party with multi-player gaming... the reason is, it's just far too noisy for movies or peaceful gaming! It's actually awful, even if the picture and sound is pretty OK. Most of the time when I do any gaming on it (late nights), I use headphones so I don't need to hear the damm machine, but that feels so wrong to 'have' to use headphones.
Even my HTPC and projector put together don't even make half the noise as the Xbox 360 does!
I'm still unsure and unclear on whether the newer Xbox 360's make as much noise? ...and I'm not wasting more money on my Xbox 360 with a hybrid Lian li case.
PS3 hasn't this issue, but then it's such a 'boring' machine when it comes to games. The only games that seem worth playing are either budget games available on-line, like Wipe-out HD or those available on the PC as well... and on the PC, the games are far better graphically and audio-ably, especially on a big screen!