Yes, no problem. Remember the "speed grade" is actually the MAXIMUM speed you may run the DIMM at. If the board can't reach that far up, the DIMM will be a bit bored but work nonetheless. (The lower speed limit for DDR SDRAM is 83 MHz.)
On the K7S5A, I've been using PC3200 CL2.5 RAM myself. It lets you tweak the RAM timings to most aggressive (including CL2!), and still runs nicely.