Here's my logic for going for the quad-core models over the dual-core models (coming from someone who bought the dual-core model and has since returned it and has a quad-core i7 model on order):
This is a fairly major update from Apple, they've made a ton of useful changes including the display which you're not going to want to replace any time soon. I see this particular system as something to keep for 2-3 years minimum so you're going to want as much bang for your buck over that period.
Snow Leopard is a clear indication by Apple of their intentions of supporting multi-core applications through Grand Central Dispatch. Having a quad-core machine will likely prove to be a massive boost to performance in the coming years as more developers develop to take advantage of GCD. Having four cores a year from now vs two may prove to be a massive difference in terms of performance, certainly more so than is currently the case but if you're about to spend £1300+ on a new computer you're going to want to set yourself up as best as possible for the future for a small upgrade cost.
Secondly, if it was simply the case of a Core 2 Duo or Core 2 Quad, I could still recommend the quad-core CPU for the reason stated above but the fact that Apple is offering the i5 and i7 processors means that not only are you going to gain in the medium and long term from the extra cores, but these new processors are of an entirely new architecture which is likely to be the dominant platform in the coming year or two. The i5/i7 processors are faster clock for clock, they have more cores, they're more power efficient and they have turbo boost which gives you a speed boost where less cores are required. Ultimately I feel that buying into an emerging CPU architecture will set you up much better for the future than buying into a CPU architecture that is very much on its last legs in terms of industry support (seems to me like the entire PC world has moved to the new i5/i7 CPUs rather than the Core 2 Duos).
In addition, if you go for the i7 you benefit from faster clock speeds but also hyperthreading which can be a big benefit to virtualisation (according to October's System Guide at ArsTechnica).
My overall point is that if you're about to spend £1300+ on a new computer, go for one which sets you up for a 2-3year+ ownership period with maximum performance over that time. You may get the Core 2 Duo model and regret it a year from now as Grand Central Dispatch is being heavily used and you could really use those two extra cores and more advanced architecture technology.
This is a fairly major update from Apple, they've made a ton of useful changes including the display which you're not going to want to replace any time soon. I see this particular system as something to keep for 2-3 years minimum so you're going to want as much bang for your buck over that period.
Snow Leopard is a clear indication by Apple of their intentions of supporting multi-core applications through Grand Central Dispatch. Having a quad-core machine will likely prove to be a massive boost to performance in the coming years as more developers develop to take advantage of GCD. Having four cores a year from now vs two may prove to be a massive difference in terms of performance, certainly more so than is currently the case but if you're about to spend £1300+ on a new computer you're going to want to set yourself up as best as possible for the future for a small upgrade cost.
Secondly, if it was simply the case of a Core 2 Duo or Core 2 Quad, I could still recommend the quad-core CPU for the reason stated above but the fact that Apple is offering the i5 and i7 processors means that not only are you going to gain in the medium and long term from the extra cores, but these new processors are of an entirely new architecture which is likely to be the dominant platform in the coming year or two. The i5/i7 processors are faster clock for clock, they have more cores, they're more power efficient and they have turbo boost which gives you a speed boost where less cores are required. Ultimately I feel that buying into an emerging CPU architecture will set you up much better for the future than buying into a CPU architecture that is very much on its last legs in terms of industry support (seems to me like the entire PC world has moved to the new i5/i7 CPUs rather than the Core 2 Duos).
In addition, if you go for the i7 you benefit from faster clock speeds but also hyperthreading which can be a big benefit to virtualisation (according to October's System Guide at ArsTechnica).
My overall point is that if you're about to spend £1300+ on a new computer, go for one which sets you up for a 2-3year+ ownership period with maximum performance over that time. You may get the Core 2 Duo model and regret it a year from now as Grand Central Dispatch is being heavily used and you could really use those two extra cores and more advanced architecture technology.
