Interop success

Actually, what Microsoft did makes business sense: if they'd used the option, some of their
customers would have found that switching from XP to Vista breaks the client on their network.
This would contribute to slow adoption of Vista, which has been a real problem for them. It's
much better politically for them to do it in SP 2 or something, by which point their users
will probably have upgrades Samba for other reasons anyway and when it doesn't reflect badly
on Vista in general if there are awkwardnesses.