Really? So does my car have a tire tax, just because it comes with tires on it? If you're buying a PC, 99.99% of all people expect it to come with an OS. In fact, it's cheaper to buy a PC preloaded with Windows ($35) than it is to buy an unloaded PC and buy a copy of Windows ($150). There are major manufacturers making Linux PCs. There are major manufacturers that will sell you a box loaded with FreeDOS. There's even a major manufacturer that sells pre-installed, well-supported, and beautiful Unix PCs (I've heard they're one of the richest companies in the world). It's not like Microsoft is literally taxing computers, they're charging an incredibly small amount of money and in return you're getting their OS preinstalled like most of the market wants.
Can we get over the Windows Tax thing? It's pretty much akin to saying Micro$oft. Funny in middle school, but it makes your argument much less attractive now.