I agree that people need to realize that software eventually dies and that they should be transition to something newer and supported, but with Linux you have the source code so you or anyone can take a crack and updating it if you really desire.
I wasn't aware that MS would take a contract to update something older like Win95 or WinXP, where do you get that?
MS did deal with the security issues of XP, it's called Vista and Win7. Whether you like that they made them full releases instead of service packs is irrelevant and is totally their call as it's their product. The security and driver changes were so huge that I agree that the resulting OS shouldn't be called XP.