Just because it's not supported don't go all dumb and assume nobody uses it.
I think thats the idea though....by making obsolete older OSs and not supporting them, MS is essentially forcing consumers to go get their latest products or fall behind. It sucks but.....you either use it or you don't.
I know that there are numerous government sectors that still uses OS from the 90s, but most are aware of the up and comming inevitable changes and have begin budget plans for the upgrade changeover. The company I'm working for has already began refactoring older government web apps to the .net 2.0 platform for the ongoing BRAC project for the Navy and DOD. And I must say, .net 2.0 is quite better to work with than constantly debugging older .ASP and .PHP stuff.