IMac :: Dual-core Still Faster Than Quad's?

I was taken aback by a recent review of the new iMac that has the dual-core i5 upgrade. There were claims that the dual-core i5 (i5-680 @ 3.6GHz) is still faster in quite a few applications than the quad-core i5 (i5-760 @ 2.8GHz)... Isn't Turbo Boost supposed to take it up to 3.33GHz? (yes, I know, it will only kick in if the temps allow it and it's still slightly less than 3.6 but you get my point)

Then, there was another article which claimed that even the Core i3-550 @ 3.2GHz is supposedly faster than the quad-core i5 @ 2.8GHz in a few scenarios. I realize that the Core i3 does not have Turbo Boost, but it does have Hyper-Threading which OS X sees as 4 (virtual) cores. The Core i5 does not have Hyper-threading, but it has 4 "actual" cores, and it also has Turbo Boost. Hmmm...

I have to take my iMac in because of a hardware issue and I was planning on upgrading to the Quad-core i5 for $275 extra ($300 minus student discount). I'm even contemplating jumping all the way to the i7 for another $180. Should I do this or just get another one w/ Core i3 3.2GHz? Towards the end of the article, Macworld even suggests not getting the Quad, unless "...you can take advantage of the few programs that exist today that can take advantage of the extra cores."

Future-proofing is not that important in my case, as I switch computers too often. Otherwise, quad-core would be the obvious choice, although we've been hearing the whole "Well, maybe not today, but in a year or two from now, you'll appreciate the fact that you got a Quad...", etc. since...well, almost 2 years ago.