Hoverboy, to answer your questions, I've tried RC1 and RC2 of WinXP. I have found both builds to be a lot less stable than Win2k, had many compatibility problems with hardware (which I'm sure will be resolved soon after release) and far too many compatibility problems with software, including a complete inablility to run 3DS Max R4 license server, thus making it impossible to launch the app, infinite tweaking and screwing around with CounterStrike and Max Payne to get them to work, and even when they did work, they crashed frequently to the desktop and had all kinds of display problems, GameSpy Arcade also required fiddling to get it running. Then there's the ever popular inability to share "Program Files", "Windows" or "My Documents" folders over a network, not a bug, but a documented feature with no way to disable it. As for the WPA, I don't have as much of a problem with it as many do, I don't feel it's an invasion of my privacy, but my two objections are that as someone who reformats regularly, it will be a real pain, and secondly, it's undoubtedly MS pushing towards their whole .Net subscription based software idea, which I'm not too fond of at all.
So your main arguments are compatibility, which I completely disagree with, so we'll have to agree to disagree on that one based on our own personal experiences.
New features that XP offers are skinning (windowblinds, desktopX, etc) and remote control (PCAnywhere, RemotelyAnywhere, VNC). My point is that XP doesn't offer anything at all that you can't already do (better in my opinion) with third party products for a hell of a lot less cash.
XP is a horrible monster, and I pray for its death.