Module Builder is created as an MS Access MDE.  If you do not have a copy of MS Access you will need to download and install the free Access runtime version.
Get Access 2003 Runtime from the downloads forum.

A working DotNetNuke installation, preferrably  in a development environment

Optionally;

If you wish to customize the modules once they are built you will need a .Net IDE, such as Visual Web Developer Express.
Get VWD Express here:  Click Me

We also recommend you have a Sql Server Express management tool.
Get Sql Server Express Management Tool:  Click Me