Playing an old console on a HDTV usually doesn't pose any technical problems, usually just quality. Usually
stretching out a low def signal to fit the 16:9 aspect ratio will cost you some quality.
My only word of warning is research your TV's when it comes to lag. I bought a Samsung TV and couldn't play my
PS2 on it. There was about a 1 second delay between button presses and it actually happening. So playing my old Guitar
Hero was impossible due to that lag. So make sure that the TV will support that signal or has some way for you to
calibrate the lag.
I have a Sony Bravia TV and it has no lag issues at all, even with the old consoles. I've also seen the Vizio LCD
TV's usually don't either, and they are a great deal for the money.
Best of luck with the purchase.