2003 ? Nooot that bad ...
Some are still on 2000 - one of our customers complained when we ditched support for 2000 a few years ago, so we re-instated it. This time round, we asked again if they had had the time to migrate in the meantime ... nope!
Apparently their last Windows Server in the data center is still on 2000 Advanced Server.
But Windows admins are not the only nostalgic in our customer base, one HP-UX/Solaris shop (yes, they have both), are on kit dating back to the mid 90's, no idea where they get the spares for that, though.
Solaris is not so much a problem for us, however, our HP-UX kit from that time is long gone ...