My first gaming PC

Hello everyone! I have been wanting to build a gaming PC for a while, and after brother brother building his own (He built the $600 gaming rig with a Bit Fenix case, Gigabyte HD7850 graphics card, etc.) I don't have the same budget, around $400 at the absolute most, but I would like to stay under so that I can afford a nce gaming keyboard and mouse in the near-ish future.

So anyways, I am looking at a couple different options, and had some questions; the most recent $350 PC that Logan put together seems to be pretty solid, but I was wondering if the  case/ power supply could be switched out for this, which would save quite a bit of money http://www.newegg.com/Product/Product.aspx?Item=N82E16811148047 I am skeptical, however because I realize the importance of a good power supply. NAy alternatives/feedback about this option are apprecitated.  I was also wondering if the A10- 5800K is the best CPU option for this price range; I found an intel G620 for only $77 and I wonder how much of a difference there is in performance. 

Just to clarify, I don't plan on doing any sort of hard-core gaming with this thing, and I will almost certainly upgrade this machine in the future, but for now, when I'll be playing mostly Half Life 1 and 2, Portal 1 and 2, the walking dead, and whatever other amazing deals steam has with their next sale will it suffice? Thank you to everyone, and please, no fanboys...

that psu is not 80+ certisfied and that is a big nono. i'm not an expert but that came from logan off of some video. If you whant this is the pc im building on a $400 budget.  http://secure.newegg.com/WishList/PublicWishDetail.aspx?WishListNumber=21582186  

If I were you I would get either a A10 or a A8 then get a graphics card later.  The cx430 for a PSU and a Roswell case. http://www.newegg.com/Product/Product.aspx?Item=N82E16817139026&Tpk=cx430

I used a foxconn kit that is a case/psu/mobo all in one: http://pcpartpicker.com/p/v43M