Having a C2D running 32M with the memory running <500Mhz will give dull results, system will be bottlenecked and tweaks might not take full effect as the system is starved for bandwidth imho.

I think 9x514 at 1:1 with 4-4-4 timings on a P35 platform won't be that hard, bare quadcores perhaps.

Even better result will show with 5:6 or 4:5 divider but that's something not everybody can do at 4-4-4 timings but at 5-5-5 again it will not be xtremely hard if you have some half decent memory.