"But Officer, everyone else was speeding too!"
If app store isn't the generic term for a store that sells apps, what is?
As for Windows, too wrongs don't make a right.
For all the people mentionining Linux - MS *lost* their initial case against Lindows, but then settled out of court to avoid the risk of losing altogether. If Apple want to bring a case against the use of Windows, then they should do so. Chances are, they would win.
But that doesn't given them the right to claim ownership too to parts of the English language.
"But Officer, everyone else was speeding too!"
(Also GatesFanbois makes a good point - whilst MS's trademark is dubious, at least they don't have the cheek to sue people who are using the term "Windows" in its generic computing sense.)
"They could have taken the market by storm if they'd thought of the app store concept back then"
Nokia _did_ take the market by storm - and still are the number one smartphone and phone company. Don't let the media obsession with Apple fool you. (Although yes, it's true - I bet they wish they had thought of the app store idea of palming 30% profit off of software developers. Personally as a developer, I wish no company had thought of this...)
"but there wasn't anything like a uniform app buying experience before Apple introduced their app store. ... or a separate online store for each vendor."
Wrong, there were all kinds of online stores (both free and commercial). And if you mean uniform - well, no, it's not uniform. There's still plenty of stores for each platform; and we have multiple "offical" app stores (Nokia's, Apple's, Google's, RIM's, MS's, etc)