Start by visiting the MSDN Academic Alliance home page.
Find your "Program Administrator" at your campus by visiting School Search. Elgibility varies depending on the program you are enrolled. Personally I was required to have at least one CST course. You will need to email your Program Administrator a list of the courses that you are taking for the semester and ask them to allow you to join the MSDN Academic Alliance. Once admitted into the program you can download Windows 7 Professional x86 or x64 (~2.2GB) free of charge and burn it to a DVD using a program such as the free ImgBurn.
Other software such as Visual Studio 2008 Professional, Visual Studio .NET 2005 Professional, Windows Vista Business with SP1, Visio Professional 2007, Office Groove 2007, OneNote Professional 2007, Project Professional 2007, Sharepoint Designer 2007, and Windows XP Professional are available.
As an alternative, Microsoft has another program called Dreamspark which also offers free software to students, but with no course requirements. Verification that you are a student at a university/college is still a requirement though.
