Windows 7 Ultimate
Download the official MSDN ISO image (installer) of Windows 7 Ultimate with the Service Pack (SP1).
Windows 7 Professional
Download the official MSDN ISO image (installer) of Windows 7 Pro with the Service Pack (SP1).
Windows 7 Home Premium
Classic Windows 7 for home use. It contains everything you need for everyday use and all this at the lowest price!
Windows 7 Enterprise
This Windows 7 edition includes Windows 7 Ultimate + additional functions for business, but also these functions can be useful for home use.