please dont flame me but
in no way should you go for the p35 unless your money limited.
the 680i is a good chipset, but im leaning on the x38. although you havent listed it, im gonna tell you why its more worth it.
in the long run, like th 975x ( which is still pretty strong ) you will get support. and lots of it.
the x38 over the 680i is built for 45nm and quad cores while the 680i does support it, i imagine that the bios flash will incur more bugs.
unless you want sli or multi monitors, you wont need the 16x16x8. the x38 offers PCIe 2.0 and 16x16.
with the x38 you can expect top notch quality from manufacturers, and fancy onboard cooling etc.
also, if you must have sli, theres the new c73 and mcp 78D ( expecting nov.) that should support sli,45nm and all the rest of it.
now, why you shouldnt go for p35? because its intended as mainstream. you wont get all the features ( and thats fine as long as you dont need them) and you might not get the full 9 yards.
meanwhile you have the mature and feature packed 680i. now with that, i sugguest you look at gigabytes offering. also, the striker extreme. i tend to stray away from reference due to the fact that theyre quite bland.
and now i leave you with more $^!#T to think about.
hope it helps
