Thanks for the feedback on the serial adaptors. I am nearing the 
completion of a OS X program that runs an under $100 stepper motor 
controlled QuickTime VR rig. I plan to make instructions for schools on 
how to build the rigs available soon and to give away the software. Having 
a cheaper adaptor available and one with PC 9 pin will make things easier 
for all. I recently found some really cheap USB to Serial cables but 
haven't verified that there are OS X drivers for them yet. If I buy one 
and get it to work I will pass the info on to the list.
George