If you have a usb-serial cable (like the one availible from radio-shack) You can install it and it will create a com port for you.  it can be a pain to install the driver but if you run the included driver install utility in XP-SP2 compatibility mode it will correctly install the driver for Vista and you should have no trouble.  if do not run it in compatibility mode it does not like to recognize the driver.

 

-J