For what you do on a daily basis I'd look at the
SYSMark and
gaming results at AnandTech. You won't see a striking amount of benefit from the extra cores and hyper-threading unless you do video, transcoding, animation, some Photoshop stuff etc. Note that the E8600 DC (3.33GHz) actually outperforms the quads on tests that rely strictly on raw CPU speed (Turbo Boost won't always give you a benefit in every situation).
Unless the base, single socket Mac Pro takes a huge dive in pricing soon (and it should!!), I'll probably get a 27"/i5 for myself. My dual G5 PowerPC is being left at the side of the software road (thanks Apple & Adobe!

).