Hi marduk,
This is not a problem related to backing up games, therefore, your post is off-topic! I suggest that you ask the game manufacturer directly or ask your question on the official forum of the game.
As some kind of an answer to your question: Windows 2003, as you also wrote it, is rather for servers than home PC's so it might not be apparent for the game coders to add support for it. However, I don't think that Windows 2003 would be that much different from Windows XP, so adding that support might be relatively easy, _if_ someone hints them at it...

Good luck,
Joe
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