G'day mountjl,
The great majority of what Microsoft sells as an OS is the desktop version, and while I agree the drone doesn't need a desktop system there aren't all that many choices from Microsoft as it's basically Windows XP/Vista/Win 7 desktop or Windows Server 2003/2008 - I very much doubt they'd have put Windows server on the drones. I don't know what the prices are like where you are, but down here Windows Server is four times the price of the desktop premium version. Another aspect is I got the impression the software also includes the control software on the operator's console.
Unix and Linux have better options that the Microsoft options available and they've been around for many years, the only trouble is Microsoft goes to great efforts to make sure they do NOT work well with the Microsoft systems with ease. Also, a lot of the people in the upper management have been Microsoft only people for years and don't what is really available outside of Microsoft Windows - thus the issue with the DoD project I mentioned in my other post. However, many organisations still use the Unix and Linux servers for reliability and security reasons.
However, whatever way you try to slice this, it's a loot easier to specialise a custom system with Unix or Linux than it is with Windows, that's why so many embedded systems for manufacturing systems and white good run on special build Linux operating systems and the government hardware can be made the same way with just as much ease.
