Suggestions on My PC Build

You should add a fuzzy dice hanging on top of the rig. For better performance.

A little preference for H87M-G43 from MSI, but well, i never compared ATX format motherboards, o wanted a µATX.
What i would do if i were you :
Create a 100GB partiton on the Seagate. (I would prefer a blue caviard from WD)
Install OS and everything, and enjoy.
At reception on the SSD : ghost the OS partition. Hide OS partition on the HDD. Test it.
If everything's ok, delete OS part on HDD, resize the other part. Resize the aprt on SSD to use all space.
Yeah a bit weird all that resizes, but i don't know in advance what exactly space the SSD part will take.

Wasn't it Seagate that had the least good HDDs on the market?

Btw, you should get a 256 SSD instead, especially if you are going to partition it. (i.e. use one part for Windows, one part for programs/games that would be awesome to run with SSD - such as some Assassin's Creed games, where you can't gallop when using a HDD). You can easily add an SSD to this build at a later time, but don't forget the hassle that comes with it.

Btw, get 8GB of RAM instead of 4.

Are you going to overclock? If not you don't really need K version of that CPU. And if you are seriously in that the Z87-mobo might be better option.

A keyboard and a mouse, just uhh, noticed it wasn't on the list.

Seagate drives are very unreliable. Buy something else.

If you don't get 8 GB of RAM now, you'll have to buy 8 GB later and sell this memory stick, because you'll almost certainly have issues. It doesn't matter if you get the same model later, it'll be from a different batch, and motherboards are extremely picky these days.

H87 and overclocking don't play well together. Either go up to Z87 with the 4670K, or drop down to the non-K model for a H87 mobo.

in 6-7 months its likely that the 870 will be out. Swap out that seagate hdd for a wd black 1 tb, they are faster and come with 5 yrs warranty.

GTA 5 in 6-7 months :]

I just wouldn't trust Asrock for my system.

If you are going to add SSD later I suggest formating the HDD in two or more partitions, basicly a 100-200GB for Windows and related stuff.
Then just remove the HDD, install SSD and install Windows. Add HDD back and move all you need from windows partition and format that partition, or leave it to sit like I do because I'm lazy...