For the most part, yes.
There are features in XP that don't exist in W2K, so it's no guarantee, and it's conceivable that a programmer did something really, really oddball that works in XP but not W2K.
As long as the program doesn't install a device driver (antivirus, remote control software, defrag, some remote backup agents, etc.), chances are the answer is yes.
But it's not absolutely guaranteed. If in doubt, call the manufacturer.