It depends. If you are an Event Photographer running in Kiosk mode, you can have the photos go right to the PC running PBC, so you only need 1 computer. If you are using a Photobooth you have 2 choices. Running in Booth mode, you don't need a 2nd PC because PBC will run on the same machine as your photobooth. But running in Kiosk mode on a 2nd PC allows you to offload the time spent while people log in to their accounts away from the booth to keep the line at the booth moving.