Operating System

Microsoft

MS DOS
Windows 3.x
Windows 95, 98, ME, SE
Windows NT,2000
Windows XP Home/Professional Edition
Windows Server 2003(Standard,Enterprise)
Longhorn , Avalon (future Releases)
Windows CE, Pocket PC
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Unix / Linux

Debian (Many forums)
Red hat Linux(ES,AS)/Fedora Core(1,2,3) (USA)
SUSE Linux ( was German, but bought by Novel now USA)
Mandrake Linux (French)
Knoppix
Slackware
Free BSD, Open BSD, Net BSD (USA)
Gentoo
College Linux
Turbo linux
Yellow Dog
Cygwin(for Windows)
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Mac

Apple DOS
A/UX
ProDOS
GS/OS
Mac OS
Mac OS X (panther ,tiger)
Apple Darwin
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SUN

Solaris
Java Desktop System
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