A higher FSB at the same clock speed will not be any faster, just more difficult to achieve.
By that I mean 4x800 or 8x400 will give the same performance, but 4x800 is not achievable on any known board.
That aside, brush up on your BIOS settings, make sure you know what absolutely everything that has bearing means. Also learn the max safe voltages of your Northbridge, CPU, RAM etc, and the max. temps for your components.
This would be my method of overclocking.
First, set your CPU and RAM to stock speeds. Run Orthos for at least 10 hours to make sure it's stable, and to check the temperatures (it should stay under 70C).
Of it passes, you're ready to start overclocking.
Leave the multiplier at 9, have the RAM at a divider (also known as multiplier or ratio) of 1:1 (at stock speeds, your RAM should be at 533Mhz using this) and increase the FSB slowly. 10MHz at a time is fairly reasonable. Then, run Orthos on Blend for a while. If it's stable for, say, half an hour, up the FSB some more.
When it errors out, reboot and start playing with voltages. You'll need more VCore, possibly as you push further you may need some more voltage on the VTT and Northbridge. RAM shouldn't need more than the rated voltage. The way in which these are named will differ between boards, this is just a rough guideline.
Keep going until either the core voltage is too high (1.5V is an absolute maximum in my opinion, you could probably go higher), your temps are too high, or you're satisfied.
Run Orthos for 10+ hours. If it fails, you'll have to lower the clock speeds, and try again.
Do not use any software to overclock, you're asking for trouble.
Good luck.
