Re: OH !!
I think, don't know for sure, that the US Navy had some shipboard Windows administrative systems, not combat systems.
What little I know about the USN (more than most folks, but really not much) is that each and every ship consists of a platform with a hodegepodge of weapons systems -- some quite ancient -- crammed into any space they can find that will hold them. Further, major upgrades are done during periodic overhauls that are scheduled many years apart because of limited yard capacity, so two ships that are actually configured the same would be a rarity.
I have trouble imagining a Windows based combat system much more complex than WFWG, but the military does odd things at times. Sometimes they have good reasons. Sometimes not.