@Stardude: I won't disagree with you on your point. Still for a few ignorant (as in, not so interested) people in this thread, I'll explain the reasons behind your comment.
Windows 2000 was available only as 'Professional' and 'Server' (x3) editions - not Home. Windows Me was in development and came out roughly at the same time, and included the 'family' features: system restore, system files lockdown, an advanced media player and a basic movie maker. It was still DOS-based, but the command line mode had been removed.
As an enterprise-only edition, Windows 2000 saw no feature upgrades during its active support lifetime: changing that would have led to enterprise problems.
Windows XP (RTM, SP1) had two very specific editions: there were kernel and network differences between the 'pro' and 'home' editions only (no 'server'); meaning that features could be improved, and perfect binary compatibility was not as much of a requirement from patch to patch (that's an enterprise server requirement, not so much for the desktop).
Due to Windows XP's original codebase being mostly Win2000's with extra sprinkles (ACPI and power management were also better refined in XP), security was a definite concern. This is why Jim Allchin managed to convince Bill Gates to give away a new OS to existing customers, due to how late Longhorn was getting: at first, there was supposed to be a 'Windows XP 2003 edition' or 'XP 2' that one had to pay for, and that would contain only security enhancements over 'original' XP. Instead of that, Windows XP SP2 was the result of a massive code audit, and for the first time ever, contained real new features and an API upgrade to an existing product. This was marketing-based: customers wouldn't understand why they had to pay for a security upgrade. Just imagine: 'Windows XP 2: no new features, no higher power requirements, Just Safer. $100' is not a good marketing message - especially with OEMs.
SP2 basically contained a half-rewritten kernel (now common to both 'Home' and 'Pro' editions), recompiled/fixed binaries (for NX support), a 'new' IE (IE6 got a popup blocker and ActiveX warnings), updated DirectX (9 instead of 8), and the Security Center - but no GUI improvement, apart from a very basic GUI for the already existing firewall (which is actually much more powerful than it looks like, but you can't configure it). It also had the same, if not a lower, memory footprint than before.
Now, and that's where some people are a bit unhappy with Win7 but get it anyway, is that it's indeed 'Vista done right': a lifted up but basically identical core with extra sprinkles. Like XP (original) to 2000.
I think I'll stay on Linux for a while yet.