It might not be the PC but actually your O/S.
Your older PC was probably running DOS or a DOS based O/S (DOS, WIN3x, Win95 or Win 98). Some DOS programs won't work on newer computers running XP. We have some DOS programs that won't even work on 98/98SE and 98 is supposedly still a DOS based O/S.
The XP incompatibility has something to do with XP not allowing direct calls to the LPT port as could be done in DOS.
Try contacting the software vendor to see if they have drivers for whatever O/S that you have on your new PC. Or upgrade the software to match your newest O/S.