If you have a valid .edu email address and want to get Windows 7 for cheap then check out http://www.win741.com
Similar to Microsoft's Ultimate Steal program for Office 2007, you can pick up a copy of Windows 7 Professional for only about $65!
Also, check with your college to see if they have a program to get a copy of Windows 7 for free. It may not be available at your school but it's definitely worth it to ask your instructor/tech support team!