Maximum PC

My employer bought a bunch of HP 7900 systems that came with ATI 3470 video cards. The original desktop configuration gave each workstation two monitors. This worked fine since the 3470 had both a DVI and Displayport interfaces. They however have decided that they want some of the desks to have three monitors and (against my advice) purchased a bunch of NVIDIA GT310 cards to run the third monitor. Is it even worth my time to try to get these to work? My gut feeling is that I would experience lots of driver conflicts and other problems making the systems essentially unusable. Poking around on the interwebs I get conflicting answers. Some say it'll work fine and other say it won't work at all or with BSoD issues. Currently, we are running XP SP3 but will be upgrading to Vista at some point and 7 later in the future. In researching this I've found where Vista seems to have more problems with mixing ATI and NVIDIA than XP or 7 does.

TLDR: Will an ATI 3470 and NVIDIA GT310 both work in the same system running XP? Vista? 7?

XP technically can, but I would not at all recommend it. Vista simply can't- can't run two different video drivers. Windows 7 is probably your best bet to get this working, and there are multi-vendor solutions out there that work fine. My Alienware M11x's Optimus has both the Intel integrated and Nvidia discrete graphics run side-by-side and it works fine.

That is pretty much the info I was getting from everyplace I looked. Unfortionatly, they have already purchased all of the hardware for this project. We're talking almost 200 cards. And to top it off they are going to transition to Vista before they go to 7. They haven't given me a date to update to Vista, but it would be hell freezing over unlikely that they'd skip it. I think I'm going to propose shuffling around alot of hardware to make this work with what I I've been given. Hopefully I can end up with dual ATI systems and dual nVidia systems and not have any that are mixed.

That's exactly what I was thinking. Just have some systems with two 310s and some with two 3470s in them, and no mixed systems.