I'd start by thanking my wife profusely and repeatedly
Then realize that a lot of the info here is offered by audiophiles -
hard core audiophiles (no offense guys and gals). 10K can get you a decent HT room - not audio/video-phile quality but still a nice system that will keep you out of the local cineplex.
I'm a budget-minded-video-oriented guy so I'd
start with the display...
Some "ballpark figures" --
Panasonic PT-AE2000 1080p Projector ^$2700
Screen ^$1000
HD DVD ^$400
Receiver ^$700
Speakers ^$800
Acoustic foam/panels ^$500
Seating ^$2500
That leaves about $2K for wiring, installation, lighting, etc.