Building a Gaming Computer 1st Time?

So this is my first time building a computer and I have done a good bit of research (at least i think). I decided on all the parts I would need, and I wanted to know if they are going to work well together, and if they are good parts for my needs or if they are better than what I need or not good enough.

Basically I m looking to build a gaming computer that can run just about any game up to the PS3/XBox360 Era games smoothly with at least good if not very good graphics (I'm not looking for rdiculously high graphics here) since I will be buying a PS4 for all the really new stuff. Here's my parts list:

Tower Case:
Fractal Design "Define R5"

Solid State Drive 1:
Samsung 850 Evo 250 GB

Solid State Drive 2:
Transcend SSD370 128 GB

*Note: I have always been very conservative with my memory so don't worry about that, more just the other specs of the SSDs

Motherboard:
MSI "Z97-G45 Gaming"

CPU:
Intel Core "i5-4690K Processor"

Graphics Card:
AMD Radeon R7 370 4 GB

Optical Drive:
LG Internal UH12NS30 BD-ROM Blu-ray Optical Drive

Network Interface (Ethernet) Card:
ST1000SPEX2 PCIe Gigabit Ethernet Card

Wireless Network Card:
Asus PCE-AC68

Power Supply:
FirePower ModXStream Pro 700W
I found out that there is a good sound card already built into the motherboard.
One other thing also, is a 700W power supply too much for my build here? I know technically you can never have too much but do I need THAT much. Thanks!

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