Agilent Eagleware-Elanix is the provider of SystemView. They also provide Gensys, a similar tool for RF modeling, design and development. Follow the links to free add-on packages and toolkits.
EnTegra has an excellent overview of SystemView. They are the authors of the adaptive filter package supplied free through the Eaglware-Elanix web site.
Matlab Look for Simulink and other tools.
Mathcad can be used for simulation, modeling and data analysis, and has an extensive library of application area add-ons. Also listed on Modeling tools page.