While traveling I was listening to the “Computer Guys & Gal” edition of WAMU’s The Kojo Nnamdi Show. When the host Kojo asked for comments on Microsoft’s Windows 7 and Apple's Mac OS X Snow Leopard stories, one guest mentioned a Windows 7 upgrade chart that Microsoft initially provided to AllThingsD. To the guest’s point, this chart doesn’t make it easy for end users to understand. This chart was poorly constructed and has caused confusions while the information it presented is accurate. The truth is that the choices of moving from a previous version of Windows operating system to Windows 7 should be pretty straightforward for most users. There are really four rules you need to know upfront when dealing with upgrade options.