help please-

I have finally convinced my girlfriend to attempt to learn the game starcraft with me so that she can no longer make fun of my gaming tendencies. To play we are attempting to hook up a win 98 laptop to a win xp desktop through a null modem serial port driven cable, but I can't seem to get the two to "talk". I have used the cable and laptop to communicate successfully with another win 98 machine, suggesting that the problem lies within the XP machine and somehow "enabling" the serial port to function in this capacity. I have tried everything I can think of, including the embedded networking solutions in the desktop, the dell forums, and tech support both for the game and dell... no one has a clue.

Please help save my relationship!!! Help me game with my girlfriend!!