I've done some research and I haven't gotten definite answers. Therefore I want to double check with you guys, as many of you run multi monitor systems.

Specs (current):

P5K-SE (1x PCIe 16x)
C2D E2180
HD5770 (gen. two: dual slot)

* looking at 8400 GS || 7600GT

If I was to run the secondary video card and this card was from a different vendor (nVidia), could I get away with running just the ATi drivers? The cheapest card (8400GS) was what I was aiming at.

However, if I was to in fact get my hands on an ATi card, is there any special thing that I should be aware of through software; would I need to install special software or/ drivers?

Monitor Setup:
1x LCD 24" (ASUS) to 5770 (HDMI native) @ 1080p
2x CRT 17" (Samsung) to 5770 (VGA -> DVI) @ 1280 x 1024

** looking at **
+1 x LCD 17" (generic brand) to {secondary video card} (VGA) @ 1280 x 1024

What I am doing right now is I race with the 2 CRTs in dual monitor mode, and I have the third one turned off. What I am looking at is buying a third monitor, preferably 17" LCD, connection through DVI or VGA. Because I run XP, and even if I was running V/7, I have no intention of tweaking with software to run Eyefinity. I need to run this on a secondary monitor.

Thanks in advance

Try to go the eyefinity route if possible. It will run way better on that than with softth. Other than that i think you can get away with mixed graphics cards.

Eyefinity is probably out of the questiion. My FFB Joystick (HShifter) is XP - only, and even if I change to 7/V, I still need to get a passive DVI/HDMI -> DP adapter, which will cost even more on top of that.

So, do I need a driver to drive the secondary video card (ie. from different vendor?).

What if they are the same, in my case, ATi?

if they are the same then that would be best as you dont have to worry about driver issues. (just install one driver)
if you go with different brands then check out softth forum as someone has tried it & has it working

I would avoid mixing and matching graphics cards brands. Must be easier on the system to only have one graphics driver running.

Your biggest problem is, if these specifications are correct, is your motherboard. If your other PCIe slots are only 1x, then the secondary graphics card probably won't run in 3D mode. So you'll get triple desktop, but not triple screen gaming. I had to upgrade my motherboard to get two 8x slots, before my secondary card would run in 3D mode.

Alright. Thanks for all your input. I'll keep the X1 advice in mind, and if needed, I'll hold this off until I can do a computer overhaul, and upgrade the motherboard to multi-X16 capable board.

Thank you!