If I were you, I'd keep your current video card. I have a Dell 30" 2560x1600 and a GTX 770 4GB card(which is pretty close to what you have now), running all windows at 1080p. Full screen stacked, and I have 4 smaller VideoFX(ISboxer) windows along the right side of my screen to keep an eye on the party, click on stuff in each window, etc. I do use a 27" LG monitor on the side for web browsing, also at 1080p.

You might wonder why I run WoW @ 1080p on a 1600p monitor. My system bogs way down, even with just the main at 1600p. I've played around a bit at the higher res, and there isn't that much of a difference anyway imo.

Hope that helps you