As firepages says, I think if it has tipped, it's only recent. XP was slated a lot back in the day especially for its raw sockets however it was really the first in a new generation of OS's that combined both home and business computing and stability. Sure it may not of been brilliant until SP2 came out but when it did, it was a very good OS.
Yes I do like Win7 and yes it is very good - I can't deny that, it's on my main desktop machine and I've no intention of going back to XP but all my VMs still run XP along with my other machines purely because it is so usable and easy to get things done with. In all, a very good OS. As for support, XP came out in what.. 2000? Support ended recently for it in the last year or two if I remember correctly. Now apparently I've slated them for that. On the contrary, I did no such thing, I merely pointed out that it was such a popular OS that it forced MS to extend their support for it. I never slated them for trying to withdraw it as its only natural that they will do so at some point.