This paper presents a prototype extension of TimeNET, which allows the distributed simulation of colored stochastic Petri nets on a cluster of workstations. TimeNET is a software tool for the modeling and performability evaluation using stochastic Petri nets. Recent changes are available as beta version 4.0, and include a new XML- and Java-based graphical user interface allowing the tool to run in Windows environments. The described new module supports an optimistic distributed simulation of colored models with fine-grained partitioning. A new approach to logical time has been developed and implemented to support a truly distributed simulation of immediate transitions, global guards, and global result measures, which was not possible with existing logical time schemes.