Wow.... thats a tough one ! To be honest with you im not sure but my gut feeling is that you would need a driver for that and well im sure you could find one for Windows 95, 98 , ME (all the Dos based OSes) but im not so sure about XP. The only thing I can think of is searching on Google for "Serial input driver for XP" maybe this will turn up some programmers page and they will have what you seek

XP will say something about installing unsigned drivers and click to continue anyway !