While Microsoft is busy trying to overcome consumer opinions of its current operating system, Windows Vista, the software giant is also undergoing an internal effort to beta test the next version, called Windows 7. Last week, the company began testing an internal version of the software that it hopes to ship to attendees of its Professional Developers Conference (PDC) in late October. This build has shipped to Microsoft employees and, reportedly, close partners of the company. The build, which is referred to internally as M3 for "milestone 3," reveals a product that is very much like Windows Vista both visually and functionally. Microsoft has ported the "ribbon" user interface from Office 2007 to a number of bundled applications. As previously reported, Microsoft has tasked the team that created the ribbon UI with updating the Windows shell as well.