Okey Dokey.
First things first.
Before you go touching the FSB, make sure Asus Probe is up and running as, you need to keep an eye on the temps.
Also You need to track down a stress test program, such as Burn in Test, SiSoft, SETI, Prime 95.
Run you CPU at 100% load with on of those and Tell me what sort of temps you get.
Also whats you S Code?
oh BTW here is my 2.4b OC on a P4B533 click
here
Once you know your S Code go
here and select your CPU (a P4 2.4b 533) Then you can see what others with a CPU simaler to yours have been doing.