@Martin Maloney
Sorry, but your post makes no sense at all. I'm not sure how long you've been using a computer with XP, but you seem to state facts that prove nothing.
"XP today is responsive, stable, and you would be hard-pressed to find hardware for which native drivers were not available for it. Moreover, any software released in the last five or so years runs under it."
Well duh, most hardware AND software in use today has been developed SINCE the release of XP. As XP was released in late 2001, it would have been pretty stupid for any developer to write software for windows platforms (in the last 5 years) without including XP compatibility.
"In contrast, Vista today is slow, buggy, and it suffers from a dearth of native hardware drivers. Furthermore, your current favorite programs might not run or run only in "compatibility mode."
And the "Application Compatibility Toolkit" for XP was designed for what exactly? I remember many a "happy" time trying to get old legacy Win98 apps running on XP at first. As for drivers, sorry to tell you that XP was exactly the same to begin with, with plenty of fun testing which 98/2000 drivers would work properly (not many) or waiting for either manufacturers or third-parties to release compatible drivers.
"In short, in the Windows familty, the choice is not between XP at one year and Vista at one year. Rather, it's between a mature OS and one that, for all practical purposes, is still in beta."
Take that sentence, change "XP" for either Win 98 or Win 2k (98 more for gamers, 2k more for corporates) and then swap "Vista" for XP and I've heard it all before.
I will agree that by the time SP1 was released for XP, it was already a much more functional OS, but then it was much more popular than Vista at the time. This gave the people writing the drivers and applications more of an incentive to make their apps/devices compatible with the OS.
Vista is like the unloved, unwashed child sitting in the corner with no friends. It could grow up to be something amazing, but the likelihood is that it'll always be the one sitting in the corner examining its own bogeys.