The 360 in idle is fine it's loud but the sound isn't so much intrusive during play WOW I seriously cannot play my 360 at night.. because I have to turn the volume up and it ends up waking people up(I don't know why I need to look into it but from my room things are louder outside from within than they are in the actual room..)
I was nervous when I first turned on my 360, I knew it was loud I'd just forgotten how loud and you'd think at least the new ones and the elite would be a little quieter...
I still like my 360 though.. my PS3 gets -somewhat- loud when accessing data but other then that it's pretty damn quiet.. my PC too.. when I first turned my PC on I had to check that it was actually running by opening the case cause I didn't believe it.