Edit: /\/\ How did I not see that post?

If you're going with the second monitor you have to remember at the native resolution you're going to have to push an extra 1,612,800 pixels. That's 77% of the first choice, and that's a hell of a lot of extra number crunching. Playing Clod on the first might mean being able to play everything close to max, and on the second one everything close to medium if you want to keep the native resolutions.