For many folks, upgrading to Windows 7 will simply involve buying a new computer. Others may choose to grab an Upgrade license and make the switch on an XP- or Vista-powered PC. Will those craftier users be able to do an in-place upgrade, or will they be forced to start over (mostly) from scratch by doing a clean installation?
Conveniently, Walt Mossberg of the Wall Street Journal has posted an upgrade matrix that shows which combinations of Windows editions will support in-place upgrades.
According to the matrix, if you take the green pill (Windows 7 Home Premium), you'll only be able to do an in-place upgrade from Vista Home Basic or Vista Home Premium. Those who take the blue pill (Win7 Professional) will only be able to step up from Vista Business without reinstalling. However, those who spring up for Win7 Ultimate will get to do in-place upgrades from any edition of Vista, except for Starter.
Microsoft apparently won't support in-place upgrades from a 32-bit version of Vista to a 64-bit version of Win7, or vice versa. Also, Windows XP owners will have to make a clean install no matter which version of Windows 7 they end up with.
As you might have guessed, though, Win7 upgrade licenses should be valid regardless of which version of Windows XP or Windows Vista you're stepping up from—as long as it's legit, of course. When done on a single hard drive, the clean install process relocates the previous installation and user settings to a Windows.old directory. You can then fish out documents and settings as you please.