in games..yes. look at the system builder that toms has built this month and the last few months. even the 500 pc they try and use an intel cpu as they dont bottle neck gpu as easy as the amd cpu does. alsos the ib 3540 from microcenter is 150.00 or 40.00 more then the new egg amd chip. it only slightly slower clock speed wise then the 2500k it locked at 3.1 as it core speed.
Is there really such a difference to justify spending $100 more for the intel i5?
I say yes. It is worth it. Apart for the performance boost that you get today, at the rates games are developing, a year or two from now, you may want to upgrade from the 965 again. I bet the i5-2500K will hold on much longer & there is where your $100 goes.