Looks like Apple is doing pretty well with BSD......
Apple is doing great with BSD.
One of the nice things about BSD is it frees up Apple to spend more time on the user experience portions of their operating system. Pre-X Macintosh operating systems required a lot of retooling every time Apple made significant changes in the UI. Modernizing the pre-X OSes cost Apple a pretty penny before they scrapped those efforts and went with BSD.
Microsoft could've done well by shifting to Linux for the basis of their next generation operating system. But, given Microsoft's investment into Vista, I'm curious to see why they chose to remain proprietary for their underlying OS. I'm betting it is going to be something special. I'd be very surprised if they release a lemon like Win98.