Actually Windows XP is based on Windows NT 5.1
There is no "Windows XP Server"
There was "Windows 2000 Server" and currently "Windows 2003 Server" (based on Windows NT 5.2)
See Windows NT - From Wikipedia, the free encyclopedia.
In addition, OP is correct to say that the Apache configuration appears to be wrong:
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
robocode.diverman.com resolves to the same IP as www.mylittleweb.net
That IP resolves to basic-noxim.ellipsis.dreamhost.com
Also you'll notice in the source to http://robocode.diverman.com/, there are no absolute URLs used - so how can it be a referrer in the Apache log unless Apache is writing to the wrong log file? I seriously doubt anyone would trouble themselves with faking referrers for mylittleweb.net ...
Perl / MySQL / HTML CSS