Windows XP on my Laptop Windows XP on my desktop Windows Server 2003 SBE on my home server Windows 2003 SE on my PocketPC (PDA) CentOS linux on my Apple Laptop Windows Server 2000 on my USA dedicated server CentOS linux on my hosting servers Fedora core 5 on my VPS nodes 2,4 CentOS linux on 1,3 Debian 4 on VPS node 5 I think that's it
Linux is the first choice for most of the webmasters. There are many free and open source application you can use. If you use Windows, then you need to pay the license fee to microsoft, and the price become high, the worst is that it's not stable enough as well. So, unless you really want to build your web site using asp.net, you can choose windows. Otherwise, go Linux.