If it has 2 outputs (DVI, Analogue, or 1 of both) then yes, you can. Plug them in, select Dual View in your Monitor Advanced properties, and you're done.
Now, if you click the desktop while playing a game, the game will minimise, so be wary. I use my second monitor to display WMP11 while playing. Make sure to set the resolution of your game to match the monitor, otherwise windows on your second monitor are moved left/right.