Reasoning:
Cooler removal - Waste of money in this budget
Motherboard change - The CPU does not support overclocking so, again, a waste of money to include that unless your going to upgrade the CPU later.
RAM: 4GB is minimum - 8GB is more future proof.
Storage - Windows is ~20GB + normal programs and files = 40GB-60GB already used. The average game is ~20-30GB meaning you could only hold 2-3 games. Adding a 1TB HDD is important.
GPU GPU GPU - Why build a gaming PC to game on Intel graphics? they just SUCK! a 750 Ti is the best GPU for the money as well as being VERY energy efficient.
PSU - 550W is way to much for this build. Hell, 450W is still too much but leaves room for future upgrades.
Side Note - Windows may need to be purchased...