You can only have one running. When you start up Pro you will see Pro listed in start up window, also after starting up on main window. Go to menu bar, Tools -> Advanced, & you will notice you are connected to 5 ultrapeers which helps improve searches. With Basic you are only connected to 3 ultrapeers. These figures are higher if you are running in ultrapeer mode. Also with Pro you can download from 10 hosts per file, with Basic only 8 maximum. This helps increase download speed.