Why do you think it was designed specifically for kuka? Some thing are obviously designed (drives,rdc,safety), but why bother designing something generic that is readily available?
What if It is just one of 50000 ethernet cards on the market that kuka decided to try and test, and then chose to use? If the first one they tested worked fine, why would they bother testing other 49999 products?
You were already given several options:
Use built in ethernet port
Use generic (low cost) card
Use original kuka approved card (expensive)
What else do you need? rather than trying them out you are playing what if game...
If you want word of advice:
Create fresh archive
Create fresh hdd image
Get one or two cheap ethernet cards with PCI slot and drivers for XP. Perhaps pick ones with same chipsets as the KUKA ones (Intel,3com...)