What would be the performance difference in these two Core 2 Duos and why? For what reason would I want clock speed over FSB or vice versa?

1. 2.20 GHz, 2MB Cache, 800 MHz FSB

2. 1.86 GHz, 2MB Cache, 1066 MHz FSB

I think the one running at 2.20ghz might be a bit faster. It would also have better overclocking potential. It would have a multiplier of 11, versus the multiplier of the other being 7. I don't know if you are going to do any overclocking, but the higher multiplier makes it easier.

On the other hand, a higher fsb is better then a higher multiplier. If you have identical processors, but they have different bus speed, if one has a higher fsb it would run a little faster.

I don't think you would really notice a performance different between them. If you are going to overclock though, I would recommend the 800 fsb processor.

Hopefully I didn't confuse you too much. I think overall, the 2.20ghz one would be a little bit better, but you probably wouldn't really be able to notice the difference.

The balance of performance between the two will vary depending on the type of processing being done. The 2.2 GHz CPU will have understandably higher performance in straightout processing, mathematical algorithms etc. A CPU with the higher FSB speed will have an edge where large amounts of data are to be moved around, but a 1.86GHz processor will gain little advantage because it's unlikely to be able to saturate such a fast bus. In other words the 1066MHz FSB system has more potential to be fast, but the slower CPU can't take full advantage of it.