Longest used Operating System

[Karlos]

OS2.04 10 months
OS3.0 1992 - present (still used for testing)
OS3.1 1995 - present (still used for testing)
OS3.5 1999 - present (main 3.x partition)
OS3.9 2001 - present (secondary 3.x partition)
OS4.0b 2004 - present
MOS 0.7(?) (early demo for BPPC) - 2 weeks or so
AROS sporadically since early 2005

MS-DOS 6.2 1 year
Win95 1995 - present (old PC at parents, still gets used)
Win98 1998 - 2000
Win2K 1999 - present

MacOS 7.5.3 - used occasionally on shapeshifter
MacOS 8 - 2 years
MacOS 9 - 1 year
MacOS 10.2 - 8 months
MacOS 10.3 - 1 year

Solaris 7 months
Linux - sporadically since 2000
NetBSD - when I can be a*sed.

[Karlos]

The title says longest used and you listed a load down to 24 minutes. Why is my post bad? :-P

OS3.0 and up are all still in use on my systems.