Budget: 500ish
More specific use (what games, what programs): Movie Streaming, Minor video edits, and minor gaming
Planned time until purchase: ASAP
Do you need an Operating System?: No
Do you have any specific preferred components?: No
Do you need a sound or wireless card?: No
Do you want stock cooling or do you plan on overclocking?: Stock cooling
Do you need a monitor? mouse? keyboard?: Keyboard and mouse(not really needed though, would be nice)
Zip code/location? (Shipping costs): Las Vegas

Here if you want an SSD and 240GB storage is enough.
http://pcpartpicker.com/p/GTnZsY
Total: $504.81

Here if you don't need an SSD, with 1TB HDD
http://pcpartpicker.com/p/PbK6TW
Total: $487.71

-You changed the RAM to 2x4GB when it is better to get the 1 stick of 8GB, that way he can add another stick and get 16GB in the future if he needs it.
-Then you changed the SSD Crucial BX200 to a Sandisk SSD PLUS which is a worse SSD.
-Then you got the R7 370 which is a little cheaper but is a little weaker.
The GTX950 is about 8% faster overall then the R7 370 and has a overall 2% better value then the R7 370, so instead of spending $20 more on a case on a $500 budget, I would rather put that into the video card.
-Then there is the case where you changed it to a $50 case instead of a $30 one. Why would you even change that, the case is what you want to try to spend the least amount of money.

I'm not trying to be an ass or anything, but you said you made a fixed version of my build, when you actually made a worse version of my build.

A stick of 8 GB instead of 2x4 is just bad practice. What if ram goes bad? You're out of a computer.

Odds of your ram going bad is very unlikely. If it does, then he can go buy a new stick, it's the easiest thing to replace on your computer and one of the cheapest things as well.
What if his CPU goes bad, or if his PSU goes bad, or if his Hard Drive goes bad, or if his monitor goes bad. Same result, his computer won't function.
If his GPU goes bad, then he still has an Integrated Graphics that he can use. But anything else at all same result.
This is a $500 system, not a $2000 system where you might want to have some redundancy in place.
With 2x4GB if he ever finds that 8GB isn't enough for him he has to ditch both his 4GB sticks and get 2 new 8GB sticks.
With this setup, he will just need to purchase a new 8GB stick. This give him upgradability option for his ram for cheap.
I personally would just go with 2x8GB sticks right off the bat for $25 more on top of the $40 as it is cheaper to buy in packs of 2.

Cable management and case should not be a concern in a $500 budget. You should go with the cheapest possible case that will work for the system. For Cable management just use zip ties, honestly it doesn't even matter, won't make your PC perform any better.
There is no restrictions on the future for the case I picked. It's not like he will SLI in this system, might as well just get one better card.
*You say it's more important to get a better case then a better GPU, and you are dead wrong. The case doesn't do anything to the system performance it just houses the system. It is the least important thing in the whole build. (It's mainly for esthetics)
*Why would he even need to replace the case??? What you are saying doesn't make sense at all.
The performance difference is not huge, but it is still better and the system I provided is newer and has more options for upgradability and it's at the same price. Why wouldn't you want to get a better system for the same price?

I'm not planing upgrades, I'm giving him the option to upgrade. He doesn't need to do it, but having the option is better then not having it at all.

Overall, the system I built is better, costs the same, and gives the option of upgradability. (Remember it's an option not a requirement)
Compared to the system you built, which is not as good, costs the same, and doesn't give as much option to upgrade.

http://pcpartpicker.com/p/ZzsRZL

Base Total: $572.82
Promo Discounts: -$5.00
Mail-in Rebates: -$60.00
Shipping: $5.99
Total: $513.81