Microsoft is offering students Windows 7 for only $29.99 for those enrolled in a U.S.-based educational institution. To qualify, student must be taking at least 0.5 course credits and have either an @EDU.com email address or attend one of the institutions listed here. If your qualified, this deal will let you grab Windows 7 Professional Upgrade edition for digital download. Backup media can be optionally added to order, too, if desired.
The deal is currently being featured on Microsoft Student site, which's a valuable resource for finding great deals on Microsoft software, with links to Office 2010 for $79.95, all student deals on Microsoft Store, all free downloads from Dreamspark (professional development tools), and more.