"Obligatory build it yourself rant"
Now that that's out of the way
Storage almost by definition is a bottleneck, but in gaming you wont notice a difference except in load times. You will notice the difference between a HDD and SSD in things like boot times, program start ups and those kinds of things though.
That PSU is enough for what your after and has the necessary connectors for that 7870 upgrade.
If your just gaming, downgrade the CPU to an i5-3470. The i7's Hyperthreading doesnt help in games.
If your not overclocking, see if you can switch to a H77 board, are cheaper than Z77 and dont support overclocking.
Also you seem to think that overclocking requires time to do, a simple 4.2Ghz overclock is just a matter of changing one number in the BIOS and that's it.
Ever thought about building your own? Better parts/performance and a lot cheaper. If you don't have time, that build seems fine but I wouldn't get it because the i7 is a waste and the mobo is bad. What's your budget?
Even if you paid someone else to build the computer for you, you could save a LOT of money. ibuypower is going to rip you off.
That being said, there is no situation I can think of in which this would be a good build - you're spending way too much on the CPU and way too little on the GPU if you plan on gaming, and if it's not for gaming, well... lots of things should be changed.
Have you considered building? IBuypower is a ripoff. Its very easy http://www.youtube.com/watch?v=ea_bs5G1yYU and this is the best guide out there. If you want to do it just give me a budget and usage model and ill put something together.