I'm still on Windows 7 for my home computer, and it's still fast
Bought my last two computers from Falcon Northwest, and both are pretty powerful. My most recent one is usually well into the top 1% on speed tests. I've built my own machines in the past, however this last one was a little overboard. I do a fair amount of gaming and video editing/processing, so the speed helps.
Power Supply - SilverStone® 1500 Watt Modular
Motherboard - Asus® Rampage IV Extreme
Processor - Intel® Core™ i7 3970X 3.5GHz
Processor Cooler - Asetek® Liquid Cooling - Mach V
Memory = 1866MHz 8x8GB (64GB)
Video Card 1 - NVIDIA® GeForce® GTX TITAN 6GB
Video Card 2 - NVIDIA® GeForce® GTX TITAN 6GB
Monitor - Asus® 27" 2560x1440
Sound Card - Creative® Recon3D Fatal1ty Champion
Speakers - Logitech® Z-523 2.1
Hard Drive 1 - Crucial® M500 SSD 960GB
Hard Drive 2 - Crucial® M500 SSD 960GB
Hard Drive 3 - Crucial® M500 SSD 960GB
Hard Drive 4 - Western Digital® Green™ 3TB
Optical Drive - Asus® 12x BluRay WriterVideo