Hey Bobby. Thanks for the reply, but I guess I wasn't quite clear in my question. I have no prior experience with JTAG interfaces, and simply wanted to know if the cable that I linked was enough to program the microcontroller, or if I needed an additional USB to JTAG adapter.
I currently have an Atmel ATMEGA644A microcontroller on a custom made PCB, and I need to figure out how to program it. I didn't know if the cable sold (http://www.digilentinc.com/Products/Detail.cfm?Prod=JTAG-USB) was enough to program the board on its own, or if I needed a USB to JTAG adapter as well. Could someone please shed some light on this?