Students with an ITLabs Account at the University of Minnesota have access to a wide range of free software (legally) for their personal computer. This includes software ranging from Microsoft Windows to Microsoft Office to ProEngineer to Mathematica.
Much of this software is offered through ITLabs and can be found on the ITLabs Resources Page. The software available here includes Matlab and Mathematica. You can also sign up here for access to Microsoft Developer Network Academic Alliance, where you can get free licenses for almost any software that Microsoft makes, including the Windows Operating System from Windows XP to Windows 7 Release Candidates (Pre-Release Versions), Microsoft Office (including Word, Excel, Powerpoint, Project, and OneNote), and almost any other current releases of software they make.
Other software available to students include CAD Programs such as ProEngineer and Autodesk Inventor. ProEngineer can be downloaded for free from ProEngineer's Site. Autodesk Inventor, another 3D CAD Program can be downloaded from Autodesk's Student Site, which includes free downloads of all their current software as well as tutorials on how to use the software, a feature unique among 3D CAD Software's Student Programs.
Finally, many other Software Providers offer discounted student versions of software, which can be found by searching for Student Editions of the software you want.