My choice for my personal computer is windows xp, but for a server i would use linux

I never used a mac before, and properly never will, they are to expensive in denmark.

XP 64

of course i use windowsXP SP 2
i love it and i think i won't change it
i have very good and so quick version of it called WW (Wesomsis Windows [smart])
it have alot of features

Windows for me, Windows XP to pe exact is a great OS, to chose, come one we need more votes on this.

i use windows xp and i love it!

WinXP Sp2

 I personally Prefer using Linux.  First it s more secure then windows will ever be.  There are way to many people who are hacking there way into xp and now vista . to bother with the operating systems  unless you absolutily need them for some gaming ..  I own a computer repair and networking biz and i always suggest Linux over any other os.

But with all that said Mac OS is the runner up.  ( unix core i wonder why :-P)