Mr. Christensen,
You can change the COM# from within the Device Manager. If you right-click on MyComputer and select Properties, goto the Hardware Tab then the Device Manager button. Under the ports section will be a listing of the NI-485 ports. Call up the properties of the port you wish to change and goto the port settings tab. There should be options for baud rate, etc and an Advanced button. In the advanced menu, there should be an option in the lower left corner to change the COM# of the port.
Ryan Mosley
National Instruments, Applications Engineer
http://www.ni.com/exchange