POV-Ray just recently made the move to 64-bit binaries, and thanks to the nifty SMPOV distributed rendering utility, we've been able to make it multithreaded, as well. SMPOV spins off any number of instances of the POV-Ray renderer, and it will bisect the scene in several different ways. For this scene, the best choice was to divide the screen up horizontally between the different threads, which provides a fairly even workload.
You might want to get used to seeing the Pentium D 820 outrun the Pentium 4 670 as we step through our rendering benchmarks. Thanks to Hyper-Threading, the Pentium 4 670 benefits from adding a second rendering thread, but not like a dual-core CPU does. The P4 670 trails its competitor, the Athlon 64 FX-55, by over 30 seconds of render time, while the Pentium D 820 trounces the Athlon 64 3500+. Note, though, that with only a single thread, the Pentium D 820 is mighty slow.