The Spartan-3E DCM autoranges the CLKIN frequency. Consequently, the DFS and DLL frequency buttons on the DCM are meaningless. The speed files are updated according to the data sheet specifications.
This problem has been fixed in the latest 8.1i Service Pack available at:
http://www.xilinx.com/xlnx/xil_sw_updates_home.jspThe first service pack containing the fix is 8.1i Service Pack 1.