Honestly, for me it comes down to two simple facts.

1) I would like an OS would a better UI. 2) I don't care if it bugs you/others that they need to relearn some tasks if the UI is changed.

Obviously I don't think that change for nothing but the sake of change is a good idea, but in the case of Vista I prefer it over XP.

Yes, you should be willing to explore new interactions as computing power increases. Many advances made over the years were due to such increases in computing power. Take for example: the mouse, the windowing UI, desktop search, and spatial navigation (this one hasn't really happened yet). Each item on that list required more power than was available to the previous OS iteration. Are you suggesting that this progression has stopped and our "WIMP" (http://en.wikipedia.org/wiki/WIMP_(computing)) paradigm is the ultimate interaction with our computer?

I'm not saying that Windows 7 is leaps and bounds better than XP, but essentially that's the argument you are making. Or did I miss something?

Tell them you do not know it and cannot help. Offer to help with the OS you do use. My father is very happy using Linux (Mandriva).

As the article points out, you can set everything to act like XP. It also gives good rationalization for all of the changes discussed.