I have my retro paradise upstairs hooked to a 27" tube in the office. With my L-shaped desk it makes taking game breaks in between homework grade-flatteningly easy. Ran the N64 downstairs to my 60" Sharp for the holidays for when family comes over, and it's not too bad.
However, playing old PS1 games on the PS3 thru hdmi doesn't look half-bad. And not just the PS Store ones. Symphony of the Night is a digital copy, and my Vagrant Story on disc still looks gorgeous. That game really used the Playstation's hardware to its utmost. It looks more "stylized" than "dated."