There's also the issue of lag, which I found unbearable with my NES, SNES, and Genesis connected via composite to my Vizio.

Reportedly, there are LCD TVs with game modes that are much better about the lag. Your mileage may vary.

I kept my old 27in SDTV for my retro systems, connected with s-video or less.

I use unofficial component video cables for PS2 and Xbox on the Vizio, and they work great.