If you are looking for drivers for Vista (32 bit), you can contact Digi tech support. They do have the Vista drivers, but these are not certified by Microsoft.
This are the drivers for the XBIB-U that are for windows XP, but they work well on vista home premium(32-bits), also to fin new drivers you should try to look on the support tag, then select the product X-CTU, because you could use the XBIB-U to work with the X-CTU and to do that you need the usd drivers
For my sake (since I know I’ll come back here looking for this answer again…) and for anyone else that has had trouble installing these drivers on XP, here is a handy note: Plug in the device after downloading the drivers and then use the new hardware wizard to find those downloaded drivers and install them. You have to let this process happen twice because there are technically 2 drivers (one for the board itself and one for the custom USB port setup).