Yep as Cob said get it up to around 480 FSB 3.84ghz then you have a good chip, no offence meant, but 450 is not a landmark overclock for that chip board combo.
My Q9300 sits everyday at 3.5ghz 467x7.5 on 1.34v in bios (less with cpu-z) and has been since new, did have 490 fsb out of it for a benchmark run.
Wont do that now though as it is tired made the mistake of giving to much FSB termination volts through it, not understanding what it was. A P5Q is probably a better overclocking board than my P5E even with mine being totaly under water apart from SB which has a solid copper heatsink.
So keep going and report back to us on your progress, if you need settings just ask on forum plenty of us will help you out.