50% more than whom?
Windows still requires hardware to run (captain obvious moment, I know). Microsoft forced their way into OEMs with some crazy contracts back in the DOS/Win 3.1 days and earned an anti-trust suit from the US government over it (along with bundling IE with Windows, but Microsoft did force vendors into some interesting contracts to be the sole OS they used).
And the last time I built a PC the hardware came up to be more expensive than a Mac and I had to buy an OEM version of Windows to go along with it. Seems I still had to acquire hardware to run that OS, and an iMac was damn similar in specs (2006). That PC runs Ubuntu now and I have an iMac. And I upgraded the RAM in my iMac from 1GB to 3GB by purchasing a 2GB SODIMM from new egg that cost less than $50.
My point is while Microsoft does not produce PC hardware, they certainly work with hardware manufacturers and PC manufacturers to get the product out. Whether you chose a PC with Windows or a Mac you are still buying hardware irregardless of the source.