That would also work...

Heck, if you're going to have visual stuff in there anyway...

Get a plasma. Make sure it has a VGA input and also an anti-burn in mode that can subtley shift images. Find a suitable quiet low power PC to stick in your audio cabinet, and set it to automatically cycle through some arty-farty images. Linux would rock for doing this - run X with no window manager, and have the startup script run xv -root -rm 5 -maxpect -wait 3600 -wloop somedir/*.jpg after X starts.
Find a carpenter to make a nice arty frame for the plasma so taht it looks like a painting hung on the wall.

Plain white room, empeg mounted into the wall about 2 feet off the floor, white sofa on the other side with a mirror above it, which is partially reflective and disguises the projector behind it. NXT flat speakers mounted flush into the wall in the appropriate places. The ultimate stealth install.

Do it right, with the power off it looks like something you'd lock someone in for a few days if you wanted to get information out of them

pca

> Plain white room

Stop there. Being a confirmed minimalist, that sounds about right to me. Maybe I'd add a chair if I'm feeling like adding a bit of clutter to the room to give it that 'lived-in' look.