Help with a $600 build for my son?

World of Warcraft is a game that isn't well threaded so it doesn't seem to take advantage of multiple cores well.

Thus, it does much better in INTEL CPU's like the one you've mentioned. I couldn't find an i3 benchmark but you can see this by comparing two different ones:
1) core scaling: http://www.tomshardware.com/reviews/world-of-warcraft-cataclysm-directx-11-performance,2793-9.html
2) AMD vs Intel: http://www.tomshardware.com/reviews/core-i7-3970x-sandy-bridge-e-benchmark,3348-13.html

This may vary slightly based on other parameters but it appears that putting the budget towards that CPU is best to save money for other parts.

I'll just post this, then look at your build a bit more.

it is satisfactory .i5 4670 will deliver up to 25% more frames per second

The build looks good as it is, but I would definately drop the sound card and use that money to get more ram (2x4gb kit) or a better gpu. If you stick with 4gb of ram though, get a 2x2gb dual channel kit.

http://pcpartpicker.com/p/2vNoz

My BUILD is above. It was $34 more than yours, and it requires some explanation.

1) Motherboard:
This was the hardest choice, but I'm not comfortable with the cheaper MSI motherboards. It's hard to find any reviews, so I decided on an Asus micro-ATX instead.

2) No SOUND CARD.
It wasn't in the budget for my build, and it's something you can add later as there is onboard sound already.

3) 8GB DDR3 memory.
- first, you got 1 stick of 1333MHz so you would likely have a bottleneck issue (operates in single-channel with 1 stick)
- secondly, while 4GB should be "enough" for WOW, without a huge explanation I think 8GB is worth it. It was about $23 more if comparing 2-kit sticks

4) DVD drive:
You didn't have one listed so I added one. You didn't mention not needing one.

5) CASE:
The one you chose had pretty poor customer feedback. Note the one I chose is doesn't support larger ATX motherboards, just micro-ATX (and mini-ITX).

6) Power Supply:
The one you chose was "okay" but there have been issues. I researched it after I bought the SAME ONE and it blew up. I think the Antec I chose is much better. Sure, it's a tiny bit more money but worth it I think and it supports a better graphics card as well for future upgrades if needed.

7) Graphics Card:
There's a better Asus version with custom cooler for the same price.

8) Windows 8.1 64-bit:
Windows 8 is superior in many ways, and the new interface is easily avoided with Start8 from Stardock ($5) or a free program. I strongly recommend Windows 8. I've been testing it for over a year and it's better overall than Windows 7 aside from the interface issue (again, easily fixed).

9) Hard Drive:
I got a 1TB drive for about $10 more than the 320GB listed. I think that's worth it.

10) CPU COOLER:
I didn't include one, but I'd had the budget I would have put in a $30 cooler like the Cooler Master Hyper 212 EVO. The Intel stock one is noisier, but if it bothers you then look into options like I just mentioned. (Make sure to get the FAN CONTROL software working for the CPU.)

SUMMARY:
A lot of little changes, but all with good reason IMO. It's your build so take the advice any way you want. Balancing a build on a budget is a tricky business and $10 here and there can really add up. Advice like "get an i5-4670 because it will boost frame rates by 25%" is very poor advice if there's no money left over for a graphics card.

I wish you luck, and if you want me to post a quick build guide (already created) I'd be happy to, then you can PRINT IT for reference on building and installing Windows.

GOOD LUCK!

i didnt say Get i5 4670 . i said that it is satisfactory . Also cant you see the word "UP to"

whitecat,
I didn't mean to appear rude, but you can't just recommend a particular CPU that costs more money unless you can justify that inside the BUDGET, though I wouldn't mind seeing a link showing the i5-4670 performing that much better than the chosen i3-4130 in WOW because I couldn't find one (not saying you are wrong).

Unless something has changed and I've found no evidence it has, WOW doesn't benefit much beyond two good cores (comparing the same CPU architecture and frequency):
http://www.tomshardware.com/reviews/world-of-warcraft-cataclysm-directx-11-performance,2793-9.html

We both went a little over budget already, and the i5-4670 costs $95 more than the i3-4130. That would leave $55 for the graphics card because basically there's NOWHERE ELSE to save the money and stay near the budget.

The trick is about BALANCING all the parts.

Do you read other s posts at all ?! he asked a question and i just answered it . i didnt recommend anything .. i think i3 4130 is enough . the link will send you in a moment . Since the site is not in English i dont post it - who would read it ? it is from Germany.