i picked up a Samsung 22" widescreen a few months ago. they're pretty quality. its got a 2ms response time. anything under 5 ms should be ok for gaming, anything more than 5 ms will give you that ugly ghosting effect.
id be sure to actually see the monitor in action before you buy though, simply cuz of this... my friend picked up the exact same monitor i have after i showed him mine, and his has a terrible bleed through problem with the backlight right in the center of the screen. its ok with colors but if your viewing anything dark like a game like doom3 the whole center of the picture is hard to see.