You're not serious are you?
I think he is, and could be right. The core i7 is definetly a fast, poweerful processor and handles many tasks much better than an E8400/E8500, but in AH, the noticeable change is proabably slight (not worth the extra costs associated with the CPU plus the CPU itself).
Go look at benchmarks at tomshardware.com:
http://www.tomshardware.com/reviews/core-2-overclock,2146.html (February System Builder Marathon or SBM)
Also look at the two prevous months' Marathons as they compare the E8500 and the Core i7 to the most recent SBM, which uses the Intel Quad 9550.
Might also be worth your while to poke around on other tech sites to understand where the i7 REALLY excels and where its JUST a little bit better than a Overclocked Dual Core.
AH won't use more than two cores anyways at this point, so the extra cores on the i7 wont really help alot, which is the main point.
Of course, if the extra $200-300 is not an issue, then you would proabbaly be better served going the i7 route as it is obvisouly the CPU architecture that will have the most longevity, and who knows, MAYBE AH (or other games) will push past dual-core use in the future....