Multi monitor set up with different size

I would imagine that there would be no difference in performance because regardless of the monitor itself the video card is still rendering the images at a certain resolution and sending it out to the monitor to display. Whether the monitor displays it at the way you want it to (22" screen vs 23" screen) is up to the monitor. You would notice no framerate difference if that's what you're asking.

What you WILL notice is that the screens are smaller on either side. Personally that'd drive me crazy and I couldn't take it, but if you're OK with that then more power to you : )

I think the newer versions of Catalyst support different resolutions on the monitors. I know they support different color/gamma settings. I'm not 100% sure about the res thing, but I think they do.

Edmundnam, if you're planning on running all 3 monitors at the same resolution, regardless of the difference in sizes of the monitors, you should be perfectly fine.