On the ML605 board, the easiest interface to use is the USB-UART bridge. On the FPGA, you would have to write a standard RS232 serial interface, and the Cypress USB-UART chip takes care of the complicated USB stuff.
On the PC, you can receive the data with Hyperterminal, MATLAB or write your own Windows program.
The interface is a bit slow (under a megabit per second) but you could easily implement it in a week ot two if you are decent at HDLs , faster if you already had the UART block and the PC-side software ready to go.
r.b.