Oh Great Sages of PC Wisdom,Share Your Knowledge!

OK, I'm finally in a position to get this new system, but I'm so far removed from my last system purchase, that I'm not sure I have put together by best system, both from a budgetary or performance perspective. My last PC build was at least 10 years ago. I became very comfortable swapping, upgrading and tweaking my systems, but have not had a working PC for over 5 years now. I've been using my iMac for everything from photo and video editing, to general day to day web surfing and other mundane chores. It's great for that, but for gaming? You can all stop laughing now...I have. My PC usage has been limited to work issued laptops.

My son is a big gamer and has finally gotten me back into the fold. I'm looking for advice on a new, killer, brag-worthy system. Researching the HELL out of anything I buy is hard wired into me. I want to know WHY I'm choosing one feature over the other, but it's been so long since I did this with a PC, that I don't know the right questions to ask and might not even understand the answers yet. I've decided to go with a Digital Storm system, though the setup is yet to be determined. I have a system I've cobbled together here, but would sure appreciate some feedback on where I can fine tune my choices.

Also, please justify why I should want Windows 10. I use it at work and HATE it. I long for my Windows 7 back and see it's an option here.


I'll appreciate ANY advice or insight you can offer.
Thank you!!!

Budget:
$3000 to $4000

Expectations:
I want to experience the new sophisticated gamesI've missed for so many years!

Usage:
Gaming, first and foremost, but I'll have to do some MS Office and Taxes too :( I would like to be able to play Star Citizen, Fallout 4, Skyrim, etc with as high a resolution as possible. A new monitor may be needed down the road.

System #1

Configuration Code: 1389149
Total Price with Instant Savings: $3,780.00

Direct Load URL: https://www.digitalstorm.com/configurator.asp?id=1389149

Specifications:
Chassis Model: Special Deal Hot Seller - Hailstorm II Edition
Exterior Finish: - Standard Factory Finish
Trim Accents: - Standard Factory Finish
Processor: Intel Core i7 6700K 4.0GHz (Codename Skylake) (Unlocked CPU) (Quad Core)
Motherboard: ASUS Z170 PRO GAMING (Intel Z170 Chipset) (Up to 5x PCI-E Devices)
System Memory: 32GB DDR4 2666MHz Digital Storm Certified Performance Series <br><strong></strong>
Power Supply: 1000W Corsair HX1000i (Digitally Controlled Power)
Expansion Bay: - No Thanks
Optical Drive: DVD-R/RW/CD-R/RW (DVD Writer 24x / CD-Writer 48x)
Storage Set 1: 1x SSD (500GB Samsung 850 EVO) <br><strong></strong>
Storage Set 2: 1x Storage (1TB Western Digital - Black Edition)
Storage Set 3: - No Thanks
RAID Config: - No Thanks
RAID Card: - No Thanks
Internet Access: High Speed Network Port (Supports High-Speed Cable / DSL / Network Connections)
Graphics Card(s): 1x NVIDIA GeForce GTX 980 Ti 6GB (EVGA HYBRID Edition) (VR Ready) <br><strong></strong>
Sound Card: Creative Sound Blaster Zx (Includes Audio Control Module) <br><strong></strong>
HPC Processor: - No Thanks
Extreme Cooling: H20: HydroLux PRO: Exotic Custom Cooling System (CPU Only)
HydroLux Tubing Style: Flexible Tubing (Requires HydroLux Liquid Cooling System)
HydroLux Fluid Color: Red Fluid (Requires HydroLux Liquid Cooling System)
Cable Management: Premium Cable Management (Strategically Routed & Organized for Airflow)
Chassis Fans: Standard Factory Chassis Fans
Internal Lighting: Remote Controlled LED Lighting System (Multiple color options and lighting effects)
Airflow Control: - No Thanks
Chassis Mods: - No Thanks
Noise Reduction: - No Thanks
LaserMark: - No Thanks
Boost Processor: Standard Intel Turbo Boost 2.0 Automatic Overclocking
Boost Graphics Card(s): - No Thanks, Please do not overclock my video card(s)
Boost OS: - No Thanks, Please do not tweak the services on the operating system
Windows OS: Microsoft Windows 10 Home (64-Bit Edition)
Recovery Tools: Windows Recovery Toolkit (Bundled with Windows CD)
Virus Protection: FREE: McAfee AntiVirus Plus (1 Year Service Activation Card) (Not Pre-installed) ($35 Value)
Office: - No Thanks
Game: - No Thanks
Display: - No Thanks
Surge Shield: - No Thanks
Speakers: - No Thanks
Keyboard: - No Thanks
Mouse: - No Thanks
Branded Gear: - No Thanks
Priority Build: - No Thanks, Ship Within 10-15 Business Days After Order Is Successfully Processed
Warranty: Life-time Expert Care with 3 Year Limited Warranty (3 Year Labor & 1 Year Part Replacement)

first of all, welcome to the forums! 

you're going to want W10 because it's supported by M$ and W7 isn't any longer.  also, as more people adopt it, and newer technology arrives, more and more game developers will be designing their games around DX12, which is only available with W10.   DX12 offers a host of performance improvements over past versions.  sure, it has its growing pains/teething issues right now, but in the long run it's better to take the plunge, now, when you are having a new system built.

as far as your build config is concerned: 

1)  you don't need an I7 for gaming and light pc work, you can save money with the I5-6600K (also, you don't need a "K" sku if you don't plan on over-clocking)

2) you don't need 32GB of system memory for gaming and the pc work you outlined.  16GB is more than enough for today's and the foreseeable future games.  you also don't need to get the fastest memory either.  you can save money here by getting an "average" 16GB DDR4 memory kit. 

3) you don't need a 1000W psu either.  not unless you plan on expanding your graphics with another 980ti, which you only need to do if you plan on 4k gaming.  a word on 4k gaming: it's not there yet.  even with the adoption of the new DP and HDMI standards, the market won't see faster than 60Hz 4k monitors for quite some time (probably years).  a single 980ti is more than capable of handling 2K (1440p) and lower resolutions just fine.  a better investment from both a financial standpoint and visual experience is to pair a single 980ti with a good/fast (120Hz or better) monitor.  for some that's an IPS (or similar tech) and for others TN paneled monitors. 

back to the matter of psu choice: a single 980ti, even oc'd, only draws in the neighborhood of 500 watts of power under load (while gaming or stress testing).  the rest of your system will draw under 200 watts (unless you cpu is oc'd as well).  personally, i like to buy more than i need because psu's do lose efficiency as they age and i know that they operate best between 40%-80% of their output.  look for a highly rated/high efficiency 750W psu.