I have a regular mouse, a spinner, a trackball,  and light gun 1&2 for a total of five devices that register as Mouse under Windows XP.  I also have two dance pads that I occasionally plug into the USB as well.  Everything works 100%. The only problem I have is that device assignment is not permanent. I.e. depending on when I plug in dance pads (before or after I boot up) light gun 1 could register as mice 1 or 2, or 3, etc.  So I have to go under the TAB menu in MAME and reassign the controls. Same for spinner, trackball, etc.  Is there any way to make sure that, for example, lightgun 1 is mouse 2 regardless of what other devices I have plugged into the USB.  Thank you for your help.