Calmira

Calmira is an alternate shell available for Windows 3.1x and up that has an appearance resembling Windows 95. A version named Calmira Longhorn is not compatible with Windows Vista, but emulates some of the visual features of that operating system.

The shell is more than a simple cosmetic upgrade, however. Much of the functionality of later 32-bit shells has been incorporated into the Calmira software. The shell has a start menu, a task bar and a desktop that all function in a similar manner to those found in the Explorer Desktop of later 32-bit Windows operating systems.

Read more about Calmira:  Development, Source Code, Modified Versions