Reading behind the excitement youve got a spartan2 on one board and a xc9000 series cpld on the other and its up to you to design the drivers for the devices on the i/o board.The spartan has selectable i/o drivers so you can have lvttl,ecl,diff outputs whatever you want,I suggest you read the spartan user guide from the xilinx website.The 9500 devices are 5 volt tolerant
cmos basically depending on how the i/o stages are powered.Again the user guide will help.
They look like nice boards so I am sure you will have fun playing with them.