Problems using two video cards

[sj1187534]

I have a PC with the ATI FireGL PCIE card that I am currently using for 2 monitors. I got a new video card ATI X1550 PRO PCI version that I want to use for a third monitor. I am able to install the new card and I am able to extend the desktop onto the 3rd monitor as well.

Now coming to the problem:
My OS is vista ultimate and whenever I drag a window into the third monitor, the PC response is slow. By this I mean, the window does not move as smoothly as it did in the other two screens. Does anyone have any idea why?
Even the windows on the first 2 screens are slow!!

 

[Snowblind]

Is the window sort of 'stuttering' along at say 1 frame a second if that makes sense?

If so it might be a driver issue. This is what happens to windows on my pcs before I've installed the relevant drivers.

 

[sj1187534]

It turns out it was a driver issue. I had to install the relevant drivers from the device manager for each of these video cards independently rather than using the drivers cd that came with the video card.