Get i5 4670k, It is good for gaming,
Pair it with "COOLER MASTER CPU COOLER HYPER 212X" you can over clock i5 4670k upto 4.3GHz or even 4.5Ghz(4.3GHz is ideal).
ASRock Z87 Pro4 Motherboard is best MOBO fro this budget, It supports SLI also.
G.Skill RipjawsX DDR3 8 GB is best value for money RAM.
LG IPS Monitor 21.5 Inches (22MP55HQ) is good monitor for this price, It has great Viewing angles,So you can enjoy movies and it has 5ms input lag It is also good for gaming. It shows accurate colors,It supports 90% sRGB color.
ASUS GRAPHICS CARD GTX 760 2GB DDR5 DC II OC EDITION is good GPU, It is factory overclocked and it also have good Cooper cooling and it will run Quietly
And Finally I am not sure about case, I will recheck tomorrow.
All the componets seem nice but I think if he is getting a nvidia card he should be buying a motherboard that supports SLI at that budget( so that if he wants he has the option to add another gtx 760 in there in the future if not I would suggest buying a 650 watt psu as it would save money and still be good even if he overclocks both CPU and GPU).
Another thing that I would like to suggest is that he should be getting a 24'' monitor as it is the standard and he would definitely like a bigger screen than the 21.5 inch one.This one seems nice: Dell ST2420L
As for the AMD build I would suggest GA 970a DS3P as it looks better(black pcb) and has a heat sink and costs the same, although it still has a 4+1 phase design like the ga-970a ds3 which means its not a very good overclocker and would only support a mild overclock.
For the price I would suggest the MSI 990FXA-GD65 as it is allround better in performance and looks (in my opinion).
Again I dont think he should be buying a 21.5 inch monitor. A 24'' one is highly suggested. Dell ST2420L