Am I building a good gaming computer?

Your on the right track, just multiple little things.

Why have you picked a p67 board? They are quite old and don't have the features of a modern, Z77 board. A good board to get is the AsRock Z77 Extreme4.
Comes with all the standard Z77 features like USB3 internal headers and PCI-E3 ports. Some advantages of the board are the LED Debug system, proper support for Crossfire/SLI (8x/8x ports), Clear CMOS button on the back I/O, power buttons on the board and supports RAM up to 2800Mhz (though you wont need that). The biggest advantage is its price.
AsRock Z77 Extreme4. $125
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Get the i5-3570k. Its essentially an Ivy Bridge 2500k. Bit better performance and supports things like PCI-E3.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

The Corsair Vengeance RAM has massive heat spreaders on them that will no doubt conflict with the Noctua heatsink (I'l come to that later). You need to get a Low Profile brand. This RAM is identical spec wise, but smaller (and cheaper it seems).
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

You can get a Seagate HDD much cheaper, and they apparently perform bit better as well.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

The Intel 520 is a good SSD, just more expensive than it should be. You can get equivalent or faster SSD's for less.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

The Noctua DH-14 is the best air cooler on the market, but is pointless unless your after massive overclocks. The Coolermaster Hyper 212 EVO is much cheaper and can easily support moderate overclocks.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Unless you are planning to use the OS multiple times, you can save yourself a bit of cash and get the OEM version.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

With all the money I'v saved you, you can easily get a GTX670, which will perform better than the HD7870.
I recommend the Gigabyte model as it has amazing cooling and is often cheaper than the other high end brands.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Mobo / CPU - Z77 is the latest and greatest and has features that are not available on the P67 boards .... it's doubtful however that those features will come into play in the life of the typical system (3 years). The WS Revolution is an expensive board, made so by it's ability to do x16 x16 GFX. While immaterial in most instances, some games did benefit substantially form the extra bandwidth on P67 .... not so w/ Z77.

If ya were willing to spend that kinda money, the board I'd recommend is the Asus Sabertooth Z77....it's an extremely overclockable board, superb OC features and 5 year warranty insures ya won't have to worry about "repair costs" down the road. Nice combo too w/ the 3570k

$438 - http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
$15 off w/ promo code BTS504, ends 8/2

Cooler - Noc has had a long reign but it's been eclipsed in thermal performance, aesthetics and warranty (5 years vs 1) by the Phanteks

http://www.vortez.net/articles_pages/phanteks_ph_tc14pe...

$80 - http://www.newegg.com/Product/Product.aspx?Item=N82E168...
$20 off w/ promo code Phanteks722, ends 7/22

Grab these 1.35 volt RAM modules to save some heat output from the CPU memory controller
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I'd stick with the WD and its 5 year warranty, Seagate Barracuda XT is faster but has 3 year warranty. Seagate Barracuda (no XT) has a measly 1 year warranty and is best avoided.

Can't see the 7870 as a choice with the 660 Ti breaking in two weeks. The Asus 670 TOP is faster than the 680 (999 fps in Guru3D game test suite) and costs ya $0.43 per frame while the 7870's 701 fps (30% slower) comes in at $0.44 frame

As for SSD's the kings of the hill are Sandforce drives w/ Toshiba premium toggle mode flash (Mushkin Chronois Deluxe - $200) the Plextor M3 ($250)and the Samsung 830 ($250)

HAF -932 was great case .... in its day .... but it's long in the tooth and eclipsed by newer designs such as the Corsair 500R
http://www.newegg.com/Product/Productcompare.aspx?Submi...|11-139-009^11-139-009-TS%2C11-139-010^11-139-010-TS

I can't see that price for a PSU that won't let you CF / SLI. These 850 watters will provide the headroom necessary for stable voltages at high overlcocks, low ripple and low noise due to not being poushed to their limits.

XFX Core Edition 850 $95 - http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Corsair TX850 V2 $125 http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Save $50 n the OS w/ OEM Edition

I prefer the Logitech combo but that's a very personal choice

Logitech G510 http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Logitech G500 http://www.newegg.com/Product/Product.aspx?Item=N82E168...