The 30" will run fine off a 30". I saw a CD MBP 128 MB X1600 run a 30" in an Apple Store, and since the X1600's in the C2D MBP's have a highher clockspeed, it'd be great.
Computer monitors aren't designed to watch TV on. Sure it'll look good, but you'll be much better off with a big Plasma/LCD from Shard or Samsung.😉