do some research! have a look around and make sure your really happy with what you choose.
As far as gaming go, its really hard to go past benq panels. One of the few brands that specifically design everything about their monitor for gamers. In particular this one, http://gaming-monitors.com/products/benq-xl2420t-professional-gaming-monitor/
, is the best of the best right now for gaming.
If your looking for CAD/gfx work you prolly want one focusing on colours and max size. But for games = benq.