Agreed, my personal favorite. One of my servers has had W2K running since 1999 and it's still going great. Win XP is pretty decent but it crashes a bit too often. Win.Net completely sucked and Win 2003 I don't use often enough to comment on.
For Linux, Mandrake 10.1 is the best I've come across. I know they renamed it to something else, but I haven't used it yet.
I run XP Pro on my main system, mainly for the native digital photo printing built right into Explorer. My daughter's system, and my laptop have Win2k, and I have another box that I run Gentoo Linux on. As of March of this year, when an app was released that sync's my Pocket PC 2003 equipped PDA to my Linux box, I could totally live without the XP box. I have been a firm believer in Win2K since it was released, and I hate that MS has such limited support for it.