I guess I lead off.

For all my desktop use, I use Windows XP Professional.

For my servers, I run FreeBSD.

ah..i have multiple choice...i have voted .

I use DOS, QNX, Linux and Windows XP on my desktops.
I run my servers on an XP system.

I've also been using a lot of ReactOS lately. Its very interesting

I keep hearing about ReactOS. From someone who has actually used it, what do you really think about it? What is it similar too?

In one word: Incredible.
The whole idea that you can run windows apps properly, at full speed, without even using windows or having to install a (from a newbie point of view) complicated OS like Linux, is simply amazing.

It isn't similar to anything right now. Freedows OS and Alliance OS attempted to do this but last I head from them was they stopped working on it. ReactOS is currently the only active project of its sort.

You'll get more information at the ReactOS Website.

use 98se for desktops mostly except for a bit of nt4 and servers i have nt4 terminal server on at the moment

never heard of reactOS, ill have to check it out. these are the 3 OSes i use from time to time: Nlited XP Pro, Vista 32 Ultimate and Kubuntu

edit: just read the FAQ about it and it seems pretty cool. hopefully it will continue to be developed and will be XP or Vista -esque in time. right now it reminds me of the 95-2000 series (aka really plain) but then again i guess you could always use window blinds

Desktop: Windows Vista
Server: Windows 2003

Main Desktop - Surfing, General Usage, Windows2000 Professional SP4.
2ndary Desktop - Gaming, WindowsXP Professional SP2.

All of my desktops/laptops run win98SE as well as my webserver.

Add me for Win98 SE (all my desktops). However, I have to use XP for latest games though.

for my desktop at home i use windows xp pro, server 2003, vista, ubuntu. i usually dualboot or will use vmware. at my school/work i manage a server with 2003 on it. the desktop i use there runs xp pro.

I'm currently dual booting Windows XP SP2 as my main OS and Windows Server 2003 SP1 as my secondary OS.

My computer at home uses a hacked out Windows XP Pro (Site License Version). By hacked out, I mean it has no service packs installed and very little Updates (save development ones like dotnet and msxml reqs) but have USB 2.0 capability.

My computer at work is actually a server that I use as my primary workstation. It wasn't originally that but I shared a production box with a manager, and then that manager decided to take that computer with him when he transferred to another department. Anyways, it runs Windows Server 2003 Standard R2.

XP Pro. on my desktop.
LinuxMint on my notebook.