Parallels USB transfer cable - driver problems

I have purchased Parallels Switch to Mac Edition.

I have installed Parallels desktop on the new iMac, and I have installed the Parallels Transporter Agent on both my WinXP Home machine, and the new iMac. When I plug in the Parallels USB Transfer cable into the PC, it looks for drivers, finds an unsigned driver, and then I get a Code 37 which prohibits the cable from being used.

Are there updated drivers available for the USB cable somewhere? Am I using the correct version of Transporter Agent?

What I thought was a smooth operation came to a sudden halt.