StarUML is an open source project to develop fast, flexible, extensible, featureful, and freely-available UML/MDA platform running on Win32 platform. The goal is a compelling replacement of commercial UML tools such as RationalRose, Together and so on.
code not touched for years, crashes during launch on latest windows 7
This hasn't been updated in 6 years. Since then UML 2.0 and 2.1 have come out. UML 1.0 is rather outdated.