airwethead,

The problem with parallel/serial FMS interface cables is that FMS can't access them in any NT-type OS (Windows NT, 2000, XP), so, these interface options are disabled in FMS under XP.

The only two cable types working under XP are:
1) FMS specific PIC based cable, whose main advantage is that it provides as many proportional channels as your TX has (up to 8).
2) TX-to-Joystick cable. Disadvantage - only 4 proportional channels (no good for heli dudes); advantage - works with any Windows based sim, which supports joystick control. (I'm flying with such a joystick interface in Windows 2000).

Hope this helps,
Boris