Here is a question to people who say that i7 is wasted on gaming... how much of the CPU do most games use? I know that ED can be particularly CPU intensive, using all 8 threads and >50% of power from my i7-4770 (not overclocked). I also know from the "rig to run elite" thread that several people have found their ED experience to be CPU locked with their GPUs not doing much at all.
An i7 will not usually boost gaming. Games (and OS) are usuallysensible enough to let the scheduler commit threads to real cores. Hyperthreading can lead to detrimental performance in some games - the microstuttering in Lotro being my particular favourite.
Hyperthreading is great at helping along with large chunks of reliably offloadable code. It's not so great at randomly changing code - which is what of a lot of games are.
The i5 has the same basic grunt with four real cores. Sure, you can get 6 and 8 and soon 12 or 16 core CPU's - but it's diminishing returns after a certain (and highly variable) point.
Certainly gaming benefits from 4 real cores, and it is always nice to have more - all depends on the budget and the games to be played I suppose.
Now, certain other software just loves cores, virtual or not, and will gladly swallow up as many as you want to throw at it. I'm sure at NASA you have absolute behemoth machines for modeling and statistics. I don't work at NASA, but I do get to play with machines that charge some serious money