Win 2K on my personal desktop. Win XP on my work laptop. Win Vista on wife's new Dell laptop. Any Winblows OS is basically the same, just fatter, and BNG (bold new graphics)with each new evolution. Why, because thats what was available and what I was familiar with. All of our servers at work run Solaris. Solaris is sweet, loads quick, and is available for Sun and X86 platforms. Very stable.