For comparison: 7 cores of an i7 930 get ~2100pps on Debianx64. Core2Duo 2.13GHz gets ~600pps on Win7 x64. Interestingly about the same performance per core although the i7 should be a faster. I set the sievesize of the i7 to 4096000 and the C2D to 2048000, not sure if those are good values, in testnet they seemed pretty fine. i7 got no blocks for over a week while the Core2Duo just found one tonight, so it's still got a lot to do with luck.
edit: Great, now you replaced your question with nvm and my post is pretty much useless.