Thanks so much for the replies! )

JimTS - the pricing isnt that much different (maybe 20-25% more because of the motherboard and DDR3 ram), but I think you're probably right about the technology - I guess it's the way processors are going.

MachineClaw - the i7 is actually quad core, but also hyperthreaded so it can function as 8 core

wimvdb - I was really hazzy about the pros and cons of 64 bit, so your explanation really helps a lot. It's also really very helpful to know that the whole poser 8/windows 7 64bit/i7 combination works in practice (that was something I had absolutely no idea about!).

Thanks again all - I think I'm probably going to go for the i7 :)