I run a Dell 30" 3008 so when I play MMO games I run it windowed so I can have stuff like IM's open, web browsers etc.. It's good for ingame downtime where you can do something else but still keep an eye on the chatlog.
It's not the end of the world. The cards run great in full screen mode, I'll give it a few days, see how I get on with it.
It would probably be cheaper to buy a second monitor to run all that stuff on than send them back and buy to 670s

Not exactly what you're looking for exactly I know but a consideration nonetheless.