The spartan3 starter kit does not have any memory other than SRAM on it, if you want to connect any type of SDRAM to it, you have to make your own adapter board to connect to it.
You can then make your own SDRAM controller or use the one generated by Xilinx's MIG to access it.
I am pretty sure you will have a lot of problems supporting any SDRAM over 66MHz on a SPARTAN3 (even 66 MHz with the connectors on that board and your own adapter board sounds tough).
Best regards,
/Farhad Abdolian