FTDI makes a very good USB to serial cable.
http://www.ftdichip.com/Documents/DataS ... TL232R.pdf
You can modify it to work with the DSATX very easily.
J2 on the DSATX maps to the 6 pin FDTI cable as follows:
J2 - FTDI Cable
4 - 5 (RX) Yellow
3 - 3 (+5V) Red
2 - 4 (TX) Orange
1 - 1 (GND) Black
The other two FTDI wires are not needed.