Compare the two you plan to buy, not the one you currently have and the most expensive one you could buy.
i7-2600K vs i7-3930K
It really all comes down to, do you have the disposable income? If you can splurge enough, then go ahead, but I'd only get the 3930K if after the other purchase, you've bought a modular quality power supply (i.e. Seasonic, Enermax, Silverstone, Corsair, Antec), a good quality SATA III SSD of at least 120GB~ (Crucial, Intel, Samsung, Mushkin, Kingston, Corsair), enough HDDs for the footage, see what I'm getting at?
I would say, only go for the 3930K if your budget is enough over $1,500 and you'll have money left over to keep you alive. :P This is no small investment, so I don't like seeing people waste money. :P Like so many people buy i7-26/700Ks, thinking they're OH SO MUCH BETTERER FOR GAMING, when really they are not meant to be better for gaming, more heavily-multithreaded tasks, and are better for gaming in maybe 2-3 games. Now if you have like $2,000, be my guest. :P Just make sure you pair a nice GPU (or two!) with it, a GOOD motherboard, the stuff I said above....
Basically, don't make the 3930K the shining diamond in the mud, get what I mean? :P Like you already said Asus X79 Pro, that's alright, and probably good enough, but don't cheap out on the GPU/SSD/PSU/RAM, these all matter.
And of course always make sure your peripherals are pleasing to you and make your gaming/computing experience the best possible.
ahhh lost myself in a rant there.