Typically to overclock your CPU, you want to manually set your CPU Voltage. Don't let the motherboard AUTO set your CPU voltage when you're over clocking.
Set your FSB to where your target goal is, bump your CPU voltage a tiny bit, reboot. If system runs stable, you're good to go. If it won't boot or freezes, bump your CPU voltage a tiny bit again, and try over.
Repeat until Awesomeness is had by all.
P.S. You may also want to see if your memory is Linked to your FSB. If it is, your changing the FSB may slow down or overclock your memory. I prefer to UnLink my memory and manually set it to stay at the 800Mhz.