1600*1200 = you don't want widescreen, right?
If you don't, probably the three most interesting monitors are:
ViewSonic VP2030b (8 ms g2g P-MVA 20" panel) - good viewing angles, contrast, black levels, colors, low video noise and decent response time but input lag reported, some backlight bleeding, response may be insufficient for fast games and a demanding gamer, also quite expensive.
Samsung 204b (5 ms TN 20" panel) - good response time, contrast, decent blacks, backlight and video noise, plus inexpensive but crappy vertical viewing angle, colors not as good as on VA or IPS panels.
NEC LCD2080UXi (16 ms S-IPS 20" panel) - decent response time, backlight and blacks, great colors and viewing angles but not really blazing fast, plus expensive and with IPS-typical panel shimmering.
If you are a heavy / hardcore / pro gamer, please take the possible flood of Dell 2405FPW recommendations with a grain of salt. It's a pretty slow monitor by today's standards, plus severe input lag has been reported, IMO a serious gamer even semi-sensitive to ghosting or high pings will detest this display, especially when coming straight from the lag-free CRT world.