It's going to be a while before alot of software takes advantage of four cores. Most games really only use two and thus perform better with a dual core CPU of higher speed rather than a quad core CPU even if they have some quad core optimization. The truth is, getting down to nitty gritty assembly in order to fully utilize four cores falls on the wrong side of diminishing returns for most game software developers. It's gonna take a while before the tools come out that let the visual c++ and visual basic programmers be able to use four cores with minimal investment as far as development time goes.
Maybe the DX11 SDK will have physics and AI threading capabilities that will let quad cores show their stuff without putting developers through developer hell, but time will tell. Knowing Microsoft I'm sure the day is soon coming when VB programmers can just drop in some premade controls and have some premade threading functions that are 40% overhead to get that 60% CPU performance on all four cores.
If you just run basic application and play a few games then forget the Quad Core, just get a dual core and be happy.
They won't have any mainstream software that takes advantage of quad core for another 2 or 3 years since over half of the systems these days only have a single core. Take for instance; my company bought 6 new computers this year and all these new computers only have a single core Pentium 3.2GHz.