This may help other people using the Olimex AVR-P40-USB. There is an error on this module (at least the one that I own). Pin 31 (TEST) of the FT232BM chip has been left floating. It should be connected to ground. Until I made this modification, the Windows 2000 drivers worked very infrequently. Usually when I connected this module to a PC USB port, Windows would indicate it found a new device but every attempt to install the FTDI drivers failed.
By the way, I did not discover this error. I found a post on the Spark Fun Electronics support forum. Here's a link to that post.