I'm just dipping a toe into multi-monitor use and have some questions.

I have a 24 inch, and a 17 inch monitor at the moment (have another 17 and 19 to use if need be later) I have a 5870 ATI card. I have both monitors plugged into the video card.

I've noticed when I extend the desktop to both screens I have some "flickering" on the second 17 inch monitor. Almost like its trying to adjust itself to something automatically. It only flickers when I scroll the mouse wheel up and down a page or move a window around, etc. Seems to happen when one screen has a browser at full screen and something might be leaking over to the other screen, not sure if I can explain it better than that.

When I create an eyefinity group even though the monitors are different I see no flickering at all, all is well.

Just wondering if this is some setting on the smaller monitor I need to look into? Its a Dell 1704FPV.

ALSO, I am assuming this videocard with two monitors on it may take a performance hit if I use it while gaming? For example have the 24 inch be the gamer monitor and have the 17 inch showing the desktop with a browser window, or teamspeak on it?

Also, I'm looking through my parts here and I have some older video cards I may look into adding one just for the second monitor on the desktop. Thoughts?

I don't know if this will be much help but I've been using 3 x 26" Eyefinity on ATI 5850 for everything I do on the pc. I do recall exactly the problem you mention when I first only had two displays, and it was for the overlap reason. I recall that with Eyefinity all monitors must ( or maybe should) be the same resolution. If you have an iPad look into Air Display, works great with Eyefinity for another display.