I have a 19" non-widescreen. Upgrading to a 22" made me...confused. Too much screen space becomes a bad thing -- it just depends on how much you can handle.
I personally prefer two monitors side-by-side. That way I can move chat windows and so on into one monitor, and have my main monitor with a managable screen size in the center. That way I can glance at the extra stuff but still focus, and there's not too much screen space at one time.