Question about using both NVidea and ATI on Mac Pro under Windows XP

I posted earlier about if I can use both a Nvidea 8800 GT and an ATI Radeon 2600 XT with my new Mac Pro. Currently it just has an ATI card and it seems like it'll work fine. The other question I have though, how will this work under VMWare? I have a Linux virtual machine but most of all I use a Windows XP Virtual Machine. Will there be a conflict between the two video cards when I use Windows XP? If so, I won't even need the ATI as much when I'm on Windows XP. Is it possible to disable that and just use the NVidea card while using Windows?

I have a 8800gt, and it works great in os x and in windows. I dont have an ATI thought so I can't tell you how they work together, but the 8800GT works very well in the mac.