Gaming / Windows Computer

Hey guys i really need your help on this one because i can't decide what to get and also because i'm a performance fanatic. Here's my sitrep, i'm willing to spend 950 € on a setup that allows me to play the latest and future games at 1920x1080 in maximum detail. I also want a good performance on winrar, quickpar, firefox (30+ tabs), I/O file operations and windows 7 itself. For gaming purposes i've chosen the ATI HD5850 and in the future i want to buy another one and make a Crossfire X so the motherboard and PSU have to support that.
The indecision starts with the CPU, the i7 860 vs i7 920, there are so many threads out there and i still can't decide, one complements the other in so many ways that it's hard to choose. I'm planning on overclocking, although i don't alot about it, only know how to increase the multiplier and clock base in the bios and that's it, either way a good motherboard and cooler are required. As for memory i chose 4 gb dual channel for the 860 and 6 gb triple channel for the 920. I have some configurations in mind and i would appreciate some input and suggestions.

Common

THERMALTAKE Strike MX Fan or Cooler Master Centurion 590 or other (must fit the 5850)
Corsair TX-750W or other (do i really need the 750w for 5850 crossfire?)
Noctua NH-U12 other
ATI HD 5850


Socket 1156

Core i7 860
Gigabyte GA-P55-UD4, UD5 or Asus P7P55D PRO, EVO or other
gskill ddr3 pc12800 ripjaws 4gb cl7 or other (the socket 1156 supports 1600mhz ?)

Socket 1366

Core i7 920
Asus P6T or other
GSkill PC12800 NQ Triple Channel 3 or 6Gb (the 3 gb is in case of budget limit)

I know the "best buy" doesn't really exist, but i would like something as closer as it can get to that. I will edit the or reply here if i remember any other factor to take into consideration.

What do you mean with problems in the motherboard quality of the LGA 1156? I've seen an article that demonstrated that the difference between 8x 8x and 16x 16x was very small, also in dual vs triple channel. What motherboard would you recommend for the 920 ?

Common

THERMALTAKE Strike MX Fan 23CM Preto - 47,75 €
Fonte Corsair TX-750W - 110,90€
Powercolor ATI HD5850 1GB DDR5 - 228€
Noctua NH-U12P SE2 - 56,75 €

Total: 443,4 €

Socket 1156

Gigabyte GA-P55-UD4 - 131,50 € or Asus P7P55D PRO 156,90€
Intel Core i7 860 - 249.8€
gskill ddr3 pc12800 ripjaws 4gb cl7 - 88,20€

Total: 494,9 € -> 938,3 €

Socket 1366

ASUS P6T - 207,40 € or Gigabyte EX58-UD4P - 210 €
INTEL CORE I7 920 D0 - 244,30 €
GSkill 6Gb DDR3 1600 MHZ - 114 €

Total: 565,7 € -> 1009,1 €

Does the 70 € difference makes up for it? Everything else i've chosen is compatible with each other? It would be troublesome to select a psu that was not enough, or a memory with mhz that are not supported, or a tower where the 5850 doesnt fit lol