Using Magic Mouse without a bluetooth enabled Mac Pro?

Get a mouse that doesn't require BT such as the Logitech MX Revolution and use it with SteerMouse - VersionTracker or MacUpdate.

Or take your computer to an Apple service center and have them install the wireless and BT cards (or just the BT module.)

Or you can try a third-party BT solution that runs off your USB port.

Buy one of the small USB adapters by Belkin that support bluetooth. The only catch with my Magic Mouse has been that you have to leave the computer on -- do not let it go to sleep. Once it sleeps, you have to go back to your USB mighty mouse, restart the MP, and then you will have full access to your Magic Mouse again.

This is not an issue for me since I leave the Mac on all the time. It puts the display to sleep, the hard drives to sleep, and everything else to sleep, except the machine itself. It works, and it's easy.

Another catch with this setup is that it does not seem to work on Bootcamp in Windows 7, but the USB mouse seems to take care of that archaic OS just fine.

Jesus