Since you're running 4 sticks of RAM, you may not get the highest possible overclock out of this. If you want to do that, then I'd suggest that you cut back to 2 sticks.
Try running 400FSB for your system, and then a memory divider of 4/3 (asynchronous mode).
Alternatively, OC your system to the highest possible FSB at 1:1 synchronous mode, and once that's done, try raising your memory divider as high as possible.
In terms of real world use, 400FSB at 1:1 is probably best in your situation.