I agree with ^ on gaming build, 1500$ is pretty much for gaming in at least a few years, but if you still want to spend 2000$ for the best, near future-proof build, consider this (no OS included)
PCPartPicker part list:
http://pcpartpicker.com/p/CzDRgs
Price breakdown by merchant: http://pcpartpicker.com/p/CzDRgs/by_merchant/
CPU: Intel Core i7-4790K 4.0GHz Quad-Core Processor ($339.99 @ Amazon)
CPU Cooler: Corsair H100i 77.0 CFM Liquid CPU Cooler ($99.98 @ OutletPC)
Motherboard: Asus MAXIMUS VII HERO ATX LGA1150 Motherboard ($208.99 @ SuperBiiz)
Memory: G.Skill Ripjaws X Series 16GB (2 x 8GB) DDR3-1600 Memory ($142.99 @ Newegg)
Storage: Samsung 840 Pro Series 128GB 2.5" Solid State Drive ($109.99 @ Best Buy)
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($74.99 @ Best Buy)
Video Card: EVGA GeForce GTX 780 Ti 3GB Superclocked ACX Video Card ($679.99 @ NCIX US)
Case: Corsair Vengeance C70 (Black) ATX Mid Tower Case ($98.99 @ Amazon)
Power Supply: Corsair 760W 80+ Platinum Certified Fully-Modular ATX Power Supply ($159.99 @ Best Buy)
Optical Drive: LG WH14NS40 Blu-Ray/DVD/CD Writer ($67.98 @ OutletPC)
Total: $1983.88
Prices include shipping, taxes, and discounts when available