I thought I would put together some information that might be useful for a Deep Thought post about some nvidia cards that can't run dos graphics in NTVDM because I found something that fixed my problem. All the research and work wasn't done by me and i'll give my sources here.

I bought an Nvidia Geforce 7600GS (PCI-E ASUS)recently.
Dosbox works great for most games, but for a few later 90's games, NTVDM is still faster. I found out that my video card, for reasons I don't completely understand couldn't make graphics using windows XP's NTVDM (for 'dos').

The computer would beep constantly and give a CPU error when I tried to run games like master of orion 2,tyrian,x-com, etc.

This post on vogons let me know what was happening, Thothie had an EVGA 7950GTKO and had the same problem I did :

All DOS Graphics Generate NTVDM CPU Error

Someone who I think is named Martin Sulak wrote a modified driver for windows XP (videoprt.sys). I don't completely understand the changes he made or the scope of this driver, but the hamster in the wheel that is my brain farted as I read his overview and downloaded the program here :

http://www.volny.cz/martin.sulak/

This post has a 'VGAtest.exe' utility that i used to confirm that all the video modes in the test work now with my card.

patch for WinXP/2000 monitor issues

Another fragment of research that someone else did, said that martin's driver should be installed in safe mode. I have only tested it installing in safe mode so that may or may not be true for people using this for the same purpose that I am.

If anybody wants to add more to this thread or rename it, please do. I want to try to have a fix available for people who run into this like I did.