I just wanted to have a post 'bout E6700 & QFX-74
Basically QFX-74 is a dual core processor not quad core !!!
it's just dual socket !!!
so if you want to to compare them in terms of price/performance ratio it's not fair , cause you're compairing a Dualplatform System against single one
Each QFX-74 will cost you 'bout 500 bucks , and if you want to make your system operational , you should install two Qfx-74 which will cost you 'bout 1000USD(not 500$) the only reason that make adopting QFX platform reasonable it's ability to support dual platform Quad core next generation K8L processors ,
and once again 'bout memory performance that someone mentioned QFX is using quad Channel Memory controller , and if the operating system supports it capability (just like Linux , Vista ,etc excluding Windows XP) it's bandwidth is double than ordinary Dual channel
so we have to wait and see some Octa-core in real world
and always remember nontheless or even non of today games, and applications are using pure horse power of SMP!!! so you won't get huge performance Gain over Quad or octa core - It's battle of Giants , don't envolve them
but honestly buying 90 nano meters QFX platform is not a good choice , cause it will consume 250 Watts just for processors
as well as the money that you needed to buy those nasty monsters , but believe me if your wallet is so full that you don't know how spend it , buy QFX70 and wait for K8L i think it worth the while

and remember you should compare QFX platform with intel Core2Quad Processors and always remember they're not Native Quad Core platform :)