Atom 330 @ 2.16 GHz:
- 4 threads, 0.66 kH/s each
- 2 threads, 0.91 kH/s each

Phenom II @ 3.6 GHz:
- 4 threads, 3.62 kH/s each

Core 2 Duo (65 nm) @ 1.5 GHz:
- 2 threads, 1.35 kH/s each

Debian/sid x86_64, latest cpuminer, CFLAGS="-O3 -march=whatever_cpu"