The reason that I recommended a quad core is that games are starting to come out that do use all 4 cores. I do stand corrected though, with most games currently on the market, the dual core will outperform due to higher clock speeds. I always like to think ahead though. I would ask yourself, how long do you want this computer to last? Obviously you are going with high enough processors that you should get a good life out of any of them. If you are the kind of person that has to have the latest, greatest, and will upgrade the cpu in a year, then the dual core with the faster clock speed would be the way to go for now. If you are the kind of person that wants bragging rights over the fastest benchmarks (it actually matters to a lot of gamers), the dual core with the faster clock would be better. If you want a computer that has the potential to last longer I would think that quad core would be better. That is of course assuming that more games are written in the future that can take advantage of quad cores (as has been said, right now, most don’t, but I assume they will).
I googled and found a benchmark that shows the difference.
Here is a chart where you can kind of get a comparison of cpu’s including some gaming benchmarks. Unfortunately, the e8600 is not on there but the e8500 is, and the clock speed is close (e8500 is 3.16, e8600 is 3.3). check the ones you want to compare on the left, and click compare to see all the benchmarks on one screen.
Fyi, the other reason that I don’t like going with the fastest clock speed out there, is cost vs performance. The e8500 is 190$ on newegg right now, the e8600 is 270$ (80$ more for 0.17 stock clock increase). Both have 6MB cash. Its possible that the e8600 overclocks better (so higher demand, higher price), but I don’t know off the top of my head. A q9400 is also 270$ (0.67 slower on the clock but quad core), and a q9550 is 325$ (2.83 so 0.50 slower on the clock but quad core). The q9650 is 550$ so 225$ more (the q9550 runs 2.83, the q9660 runs 3.00, so 225$ for a 0.17 clock increase, you really pay a premium for the fastest processor, just like with the 8500/8600).
As far as the spider platform, I’m not that farmiliar with it, but I had though it was intended to match a quad core with 4 graphics processors, streamlined through a compatible amd motherboard? Anyone know more?