Yes Darren but just as you're finding things are using the cores, you say it's time to upgrade, so was having 8 cores worthwhile when just as you found things were using them it was time to upgrade?
Meanwhile, in the i5 2500K camp...
The amount of money spent on your 2500K and motherboard was roughly what when you purchased it new? My motherboard at $100 and the 8320 at time of purchase was $160. Throw the air cooler in there for good measure because we all know AMD stock coolers are worthless and that's $290 USD. I'd guess that was probably cheaper than your setup. Also, I almost never stress my computer except for gaming and for gaming, particularly when I got it, the 8320 was equivalent in pretty much everything. Still holds true today really.
Slightly out of date but meh. Skip to 6:40 if you want to just see results.
Yeah I want to upgrade, but that's mainly because I just want to upgrade. I still am held back way more by the 7970 than the 8320 for what I do. The amount of times I'm truly limited by my CPU are few and far between and usually a result of mediocre optimization.