Question : Is it possible to install a better virtual display adapter than the one which is installed by default in Virtual XP Mode within Windows 7?

I've installed the Windows XP virtual mode on Windows 7 Enterprise and it works great!  However, we have a clinical application that needs 3d horsepower and will only run on Windows XP.  Currently it works fantastic until you need to look at a 3D image of a heart.  Is it possible to ...use the native video adapter on the host PC instead of the virtual video adapter?  I was a bit disappointed it didn't just see my Nvidia Quadro 1700fx lol.  

Answer : Is it possible to install a better virtual display adapter than the one which is installed by default in Virtual XP Mode within Windows 7?

Unfortunately no.

That is to say...so for example the virtual machine might know that there is a network card
available to use, but it doesnt know that the physical network card is a Broadcom 3c905 (for example). The virtual machine thinks that it is a pre-defined device that is written specifically for use in the virtual machine.

Same goes with other hardware, your Nvidia Quadro 1700fx would show up in the Virtual XP machine as a totally different piece of hardware. And this virtual piece of hardware does not have the features or power of the 1700f nor does it require its device drivers..

Sorry.. your only solution is to run full XP with the correct drivers for it..
.