And PCMark depends alot on your other components as well. He probably had at least 2x 10KRPM drives in RAID0, as well as high-clocked and low-latency RAM.
To the original poster: I would recommend NOT overclocking your processor. It's a fricking quad core moster that costs over a thousand dollars. It's fast enough, and what would you say if your processor suddenly died, or you halved it lifetime by overclocking it?
you know, PC benchmarks are not the end all be all of computer performance. Especially, 3dmark 06. I mean seriously, what the hell do these numbers mean in actuality?