One of the common misconceptions I've noticed with open-sorcerers is the validity and purpose of Vista. This is based not only from comments on /. but also conversations with friends based heavily in the open-source world. The comments of most open-source people can be divided into two categories; pure FUDers, and simple misunderstanding - often fed by FUDers. Well, here's my take on it...
The Vista 'upgrade' is, by most accounts a ground-up re-write of the most popular operating system on the planet that runs the biggest selection of software on the planet. As mentioned before in comments on this site, the changes are fundamental from a technical aspect - ranging from a completely new driver model to a re-written network stack. A fairly comprehensive list is available at http://en.wikipedia.org/wiki/Technical_features_new_to_Windows_Vista
The decision to do this is both a blessing and a curse. It's a blessing because the new changes are genuinely beneficial - improved kernel scheduling, better separation between driver & kernel code, improved engrained security and so on. However, currently, because of the relative freshness of the Vista code-base, it is also a curse because of the incompatibilities these changes raise in everything from driver binaries to utility apps that sit in your system-tray that can no longer "just write to the registry" without causing havoc, as you could in the shit old days when every man + dog was a local admin.
Now, for all the changes under the hood that Vista represents, does it present a reason to upgrade from XP? Well, the answer is 'no' of course - improved kernels alone don't arrant switching from a perfectly stable system. Nor does the flashy new Aero interface. In fact, I can't personally think of any reason why you'd want to convert a working OS into an unstable code-base that's been in use in production for less than 12 months.
The thing is, Vista is the OS for computers being built now and in the future. Microsoft is clearly only as big as they are now in part because of their dominance in the OEM channels; it is there they lay the groundwork for further Microsoft software to be sold.
It's a mutual relationship too of course - the OEM's want a platform that is going to run their odd boxes of magical hardware combinations with the least hassle and that will let their customers run the most software written by any Joe in his garage. Windows does that, and very well too. Proof in point is the game I'm playing right now - C a game over 10 years old, running just fine unmodified on Windows XP SP2. Could you run StarOffice from 10 years ago on Ubuntu Linux without manual modifying a single file? I think not.
But anyway, why Vista in particular? Why not XP if it works? Vista is, if nothing else, a multimedia upgrade from XP by a significant amount. It makes the bargain OEM machines look like they're not so crappy after all (Microsoft has invested billions into just how Vista looks and feels, and it shows). Not only that but you can (in theory) walk into a shop, but some 20euro game/utility for yourself and it'll probably work on Vista (probably less likely right now, but a situation that will improve). Vista/Windows is also just happens to be supported by a huge multi-billion dollar company too - OEMs have someone to sound off at when/if things go wrong.
And that is all OEM's care about - that their machines look impressive, their customers can put their own crapware on it, and that there's someone to whine about when it goes wrong. The OEM's are driving here, not Microsoft - no one buys an OS no matter how cool the backgrounds! It's the OEMs that Vista was made for in my opinion - no one cares about the new kernel enhancements in real life, they are simply evolutionary steps that possibly should've been there in the first place. Not that they go unappreciated of course, but that's another matter.
So why make kernel changes if no-one will notice in the first place? Well, some reasons include avoiding negative press - the limp security aspect of Windows previous for instance caused a right storm in the press over various holes in the OS. Second, every system has to grow in all directions. Look at Linux for instance...with almost every new build of the kernel comes newer and more efficient ways of crunching data & managing resource - the difference is changes in Linux are more of a trickle. Windows needs to keep up, but gets major overhauls rather than trickle increments which is one reason for compatibility issues as mentioned earlier.
Also, DRM. Vista supports more DRM encoded material than previous versions (which too support most DRM media). It does not convert your normal media (mp3s, jpg images, avi videos) into DRM encoded versions. It just doesn't. However, if you come by some DRM media, Vista will be able to play/view it assuming you have the rights to. It's no big deal.
The Vista upgrade in many ways reminds me of the Windows 98 > XP upgrade. That too was a huge step too, except that Windows 2000 had been out previously for business mainly that took most of the compatibility stings out of the process. Still, there was plenty of wailing & gnashing of teeth when users took this jump. It worked out fine in the end, and certainly for the better. The same will be true of Vista.
So, to conclude: Vista is an upgrade from XP visually & technically. In my opinion, it does not warrant purchasing if you have another OS running fine, but more importantly it is there to make the OEMs look good; which are the people that will really sell Vista anyway. The issues being experienced by the new changes are temporary; it will not always be this way - things will only get better with the advent of properly written software, mature drivers, and possibly a service-pack.
I can't wait for Vienna to come around so I can hear all about people protesting by saying "Sod Vienna, I'm sticking with trusty Vista!"