Windows through WinMe were pretty much "extensions" of DOS. Win98 was about the first one that really introduced the "protection layer" to keep programs from having direct disk access, but backward compatibility problems required it to allow easy overide so that old programs would still run (mostly).

NT3, and to some extent NT4, were intended to be "server grade" with all the protections built in, but they turned out to be pretty "doggy" for user machines.

Win2K (user classes) was an attempt to apply NT4 concepts, but actually make them work for ordinary users. It's not bad, but there's still a big gap between what appears to the typical user and the "special kits" you have to open for administration. You sort of have to learn to wear two different hats to really run it and to control it.

WinXP was sort of a "start from zero" thing. They looked at all the legacy stuff, but where necessary some of it was removed, and quite a lot of new things added. You can choose "Classic View" to make it look like it's similar to the "old 'uns" but it really isn't. If you try to run with inadequate hardware, or try to use a lot of non-compliant "legacy" programs it can look pretty clunky; but if you run it on an "XP Class" machine and use qualified/compliant programs, it's by far the best user OS they've come up with.

They think that XP Server is pretty good too, but I don't have any real need to know whether that's really true - for now. I suspect that, when run on appropriate hardware and "by the rules" it's probably "better" than previous Win/NT server OSs, but that's not a choice I need to make.

The "next generation" Longhorn was promised 2 or 3 years ago, and is now scheduled for 2 or 3 years from now. What I've seen is sort of scary, but maybe we'll get lucky and the vaporware will vaporize before it gets here...

John