I've not heard of anyone doing a device driver in LabVIEW though I suppose it would be possible using the Inport/Outport functions to read/write to the boards' registers. I did a little of this once and it was not a pleasant experience. Typically, these sorts of things are written in C because of the really low level i/o required and the availability of toolkits. What kind of driver did you use for Win95? Did you or someone else in your company make the board? If it was done by a vendor, are they still around and capable of providing an update? If you're stuck and have to do the work yourself, Microsoft has quite a bit of information on device driver development. One place to start is
Windows Driver Development Overview".