If your talking about an LCD Widescreen there is only one native resolution they are capable of displaying. They are not Multi-Sync like CRT monitors. If you set it at any other resolution what you get is an emulated picture from the monitor.
Gaming on a widescreen is beautiful... atleast if you run your game at the native resolution. Otherwise you get an ugly stretched pic.
FEAR at 1440x900 (my widescreen's native res.) (note: FEAR cannot display 1440x900 from its menues - you have to manually edit a config file) is BEAUTIFUL. Just make sure your vid. card can handle it.