Purely subjectively, I prefer Win2K. It leaves out some of the annoying MS frustrations of the UI, and I always seem to have much fewer settings to change right off the bat to get the OS to act the way I want. Too many wizards and little programs trying to do things for me in XP. I've found 2K to be very stable and it's been working well for me for about 4 years now.

Question for XP users: is there a way to make XP's search function to act more like Win2K's? I don't want to be presented with this option every time I open it to search for "files and folders" and whatever other options they have. I just want to search for the damn files and get that freaking dog out of there. Damn Playskool OS.