You will also need a USB-serial cable (most folks get the USB-1 from Uniden, available from Scanner Master) and install drivers to make it work, since most PCs these days don't have true serial ports. This
article discusses this - note the link for the drivers, which is the 2nd line down after the USB-1 - click on 'here' and you'll be taken to the Uniden TWiki site that has the Prolific links..