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
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)
Mac
Apple DOSA/UX
ProDOS
GS/OS
Mac OS
Mac OS X (panther ,tiger)
Apple Darwin
SUN
Solaris
Java Desktop System