First of all, I would never switch a R9 290 for a GTX 770 based on the old GK104.
The 290 is in a whole other league of performance and will be between 30 and 50% faster than the 770. The GTX 780 based on GK110 is the competition for Hawaii R9 290, not the old GTX 680/770.
Bargain hunting would make sense if the graphics card didn't fit the budget. But the truth is that it fits, and this is a gaming PC so it doesn't make much sense in cutting corners on the graphics card TBH.
Wynix's proposal for a lower cost SSD seems pretty good.
Just a little thing, if you've choosen a 4670K then you've already paid half the overclocking tax, so you should get a Z87 motherboard with it.
Actually, in Haswell
pretty much all chipsets can overclock the unlocked CPUs (changing the multiplier). The only thing they can't overclock is memory which isn't very important for gaming performance.
The chipsets vary mostly around I/O like available USB 3.0 slots, SATA3 connections and PCI-Express lanes.
Not sure about CPU requirements going down, you will get efficiency improvements with Mantle, DX12, OpenGL >= 4.4 but devs will simply use them up. (And more efficient multi-threading means CPU resources will be easier to use leading to high resource usage).
Maybe, but I'm willing to bet an arm and a leg that the CPU requirements won't go over a ~3.2GHz Haswell i5 for many years
Thanks for the amazing responses people, just 2 more questions and I think I'm done.
What's the deal with overclocking? I've never done out of fear that I might break components, but everywhere I see people seem to recommend it more or less.
Overclocking can be done pretty easily and safely with the Intel K-series and the AMD Black Series. A mild overclock could be done without changing voltages at all.
However, if you fear you might break something, then you're better off not doing it.
The Xeon E3-1230V3 that homerdog suggested seems to be a great alternative to the i5-4670K if you're not overclocking. The CPU won't reach the same >4GHz speeds when overclocked but it'll have Hyperthreading.
Also, how does cooling work? I've always had to resort to a 3-rd party one since my other computers where all basically furnaces up until the point of me buying a cooler, with GPU's pumping around 80-100 degrees Celsius.
If you buy an Intel retail CPU and you won't do any overclocking (i.e. the E3-1230V3), just stick with the bundled cooler. You'll have nothing to worry about with the new Intel CPUs as they have low TDP and lots of high-temperature safeguards. It won't go over ~65º with the bundled cooler.
The R9 290 should also be fine as long as you buy one with a custom cooler (like that MSI model). Stay away from the regular R9 290 models.
Regardless, 80-90º on load is pretty normal for a high-end GPU nowadays.