The SharePoint 2007 Test Data Population Tool(SPTDataPop) is available as a command-line executable utility which generates test data in a jiffy. This tool might be useful for performance and load testing for your project.

It takes the input from the XML file which can be configured to generate any number of SharePoint artifacts. For example we can configure it to create 200 sub sites, 500 lists each with 2000 items.

SPTDataPop is a community supported tool from Microsoft and available as a free download at CodePlex
http://www.codeplex.com/sptdatapop

More information
http://technet.microsoft.com/en-us/library/cc262198.aspx