Which video card do you own?
I've noticed that with Nvidia cards then VESA modes do not function as well under NT4/2K as well as they do under XP due to Microsoft enabling a bit more VESA access in XP.
ATI cards seem to be able to access all VESA modes fine in NT4/2K/XP with only mouse cursor access being a problem in NT4/2K in DOS games.
In the case of The Need For Speed if you have tried to run the game in a full screen NTVDM command prompt and you have executed TNFS.EXE and you just receive a blank screen and/or exit to the desktop then your only remedy is to use Connectix Viirtual PC (
www.connectix.com) and play the game within that, play the game in real DOS, or play it in Windows XP.
The game works fine for me in NT4/2K/XP with my Radeon 9700 pro but as I have mentioned before with my GF3/4 it only works in XP.