Buy Microsoft Windows 7 Enterprise with SP1 Integrated June 2012

Windows 7 Enterprise is the most advanced Windows operating system for business PCs, designed to meet the evolving needs of the users and IT professionals in your organization—both in and out of the office. With exclusive features and benefits, Windows 7 Enterprise drives lower total cost of ownership by helping your users stay productive anywhere, enhancing security and control, and simplifying PC management across your organization.

Official site