E8400 or i7 920?

This depends on what you are going to do but heck why not get the i7, better going i7(quad) than duo

You have to buy a more expensive motherboard and more expensive RAM as well though with the 920. It really depends on your needs and your budget. What graphics card are you planning on getting?

Ya its not a choice of CPU vs CPU its socket 775 vs socket 1366. You need much more expensive ram and motherboard for the i7 920.

I'd put it down as a choice between FSB vs QPI architecture. Surely FSB architecture (and LGA775) has some life left in it but now's a heck of a time to be spending a bunch of money to upgrade to a sunsetting motherboard architecture. And what if the Braidwood technology on the P57 chipset allows super-fast boots and application loads? I'm not holding my breath but it's a possibility. I can't image too many enthusiasts this Winter being glad they bought the older architecture right before a new generation of mobo's came out.

IMHO, the common sense thing to do - not withstanding a need to buy a system quickly - is to wait until Q4 2009 and see what develops in the marketplace from the P55/P57 chipset and the LGA1156 socket. Once the leap to a QPI architecture is made, the cost/benefit choice becomes dual-channel DDR3 (LGA1156) vs triple-channel DDR3 (LGA1366). And then too, a four-core/four-thread CPU vs four-core/eight-thread CPU (or maybe even only dual-core).

Personally, I have to say that I'm very impressed with the notion of a quad-core CPU that intelligently either overclocks a single core or underclocks all four cores depending on workload to maintain an optimum TDP/performance ratio. That's just awesome and all the more so in mainstream desktop products that will be affordable. All we need now are more multi-threaded apps.

OTOH, if your motherboard is a just a platform to carry the latest GPU technology, then maybe a stable and mature LGA775 mobo would be the most
efficient route until the next refresh cycle in 24-36 months. It all depends on how much money you have and what your performance priorities are, no?

The E8400/P45 combo seems to be a sweet-spot in price/performance right now. The E8400 continues to sell well and most P45 boards have very mature BIOS revisions. My entirely unscientific browsing of Newegg reviews leaves me with the impression that there are far fewer complaints about P45 mobo's than the newer X58 ones.

A motherboard is obviously a seriously complex piece of technology. Not only can it take a while to arrive at a stable and bug-free BIOS revision but the large number of I/O ports all over the board create a lot of potential failure points. It certainly helps then to buy a mobo that is well designed, manufactured and tested. The high cost of the LGA1366 socket itself along with the new QPI architecture seems to be a little problematic still for even the major mobo mfr's.

Intel recently added a fourth "VC" motherboard partner (Validation and Certification). Originally having just three VC partners (HP, Dell, and Asus), Intel shook up the market a little by adding Foxconn to the mix:
http://www.theinquirer.net/inquire [...] ipple-asus
http://www.pcper.com/comments.php?nid=7400

Kind of leaves me wondering where Gigabyte falls into the game.

Also, Intel is suing nVidia to prevent them from making QPI architecture motherboards and/or chipsets:
http://arstechnica.com/hardware/ne [...] eement.ars

Anyway, my point is that there is a lot going on in the motherboard/chipset market right now. I suspect that some of these changes will not be good for consumers.