The FSB ratio you need will be called Sync mode.
When in Sync mode, it allows the RAM to opporate in sync with the data bus it has to send information over. Sync mode will make your RAM speed equal to double the FSB.
So right now you have a stock FSB of 266. Basically your RAMs data bus is only fast enough to truly support 533 Mhz RAM, hehee!
That's why they use the multiplier. To make it look like your RAM is running at its rated speed. Even though it cant, because the data bus is to slow!
So when you set the memory frequency to sync mode. The RAM speed will be double the FSB.
That means you are safe to hit 400 x 9 for 3.6 Ghz on the CPU, and while at 400 FSB, your RAM in sync will be running at double, so 800 Mhz.