>Just as a side note...I just ran an old QB program that uses various ROM BIOS interrupts to determine what's on the system (DOS version, hard drives, mouse, numeric co-processor, etc.). With the exception of it not recognizing the floppy type (it's one of those newer high capacity types) and it not being able to properly calculate the free and total disk space, it seems to work fine.

NT virtualizes the environment for DOS systems, so if you use standard calls within a DOS session, you should be able to get most functionality. If you don't go through the standard interfaces and try to get at the raw hardware, that's where you'll be beaten to a loddy pulp...