How to use IR between a Windows XP machine and a 49/50 series machine:
Download the stable version of this driver:
http://www.ircomm2k.de/English/index.html
The driver creates a virtual COM port attached to the IR port on your PC. Start hyperterminal and choose the virtual COM port, 115200, 8, N, 1, hardware flow control. Set the calculator to IRDA, Kermit.
With this setup I had no problem beaming to and from a 50G and a 48GII using a Dell D600. Worked on the first try.
Mike