It's just funny that people will spend $2,000 on all new parts, including an extra $150 for a specific video card, some uber expensive PSU, $100 for LED lights and fans with a specific hue of 'blue'...
...and then try to cheap out $30 on the OS by buying from some dodgy site vs an actual, legal, retail purchase.
Come on, people....the OS is maybe 5-10% of the total build, at most. Just buy it from somewhere legal and reliable. If you have to ask if it is a reliable online store, it probably isn't.