The RFID USB Reader is a simple to use, USB to serial base unit for the ID-12LA and ID-20LA (not ID-20-MF7) readers. Simply plug a reader into the headers and attach a miniUSB cable. Open a terminal program of your choice at 9600bps 8N1, then scan your 125kHz ID tag and the unique 32-bit ID will be shown on the screen. The unit is based on a FTDI chip and comes with a read LED and buzzer.
More information is available on the website of Sparkfun.