Assuming you have a computer :lol: , and wanted to play your consoles on your computer monitor, just plug in a TV Tuner card, and run DScaler. Poof! You don't even need a switchbox! ;-) You might need a pretty fast PC, though, and the cheap card I got only does S-video (or composite).
I've tried this with the PS2, and it does work nicely to remove interlace flicker, but it did seem to lose a bit of vertical resolution. (It's not ideal, using s-video -- I'm sure it'd be better if I could go from component to VGA, but it's still pretty good.) I'd like to try it with the Saturn one day, which had a lot of high-res games (and no anti-flicker AA! haha).