National Instrument's does not have a developed driver for the DOS environment for the PCI-GPIB board.  There is a driver development kit available, with examples, that allow for hardware and moderate software support of the device though.  The DDK allows for support of the TNT based GPIB controllers (PCI-GPIB, PMC-GPIB, etc) in unsupported OS's.  It provides a hardware layer of code and a software layer that allow for simple development and use.  The software laye provides a substantial subset of the 488 functions but does require user development of the remaining.  More information on the NI-488DDK v1.1 can be found at:
http://www.ni.com/pdf/manuals/321418a.pdf
It is advised to contact a National Instruments' sales representative to obtain a copy of this kit.  They can be
 reached from:
http://www.ni.com/contact.htm