Even so, Microsoft's data showed that "medium" users, those with 70GB of data and 20 applications -- would spend between 1 hour and 40 minutes and 2 hours 50 minutes doing a 32-bit upgrade. (The more powerful the PC, the faster the upgrade, according to Microsoft.) Heavy users, which Microsoft posed as people with 125GB of data and 40 applications, would need between 2 hours and 40 minutes and 5 hours and 43 minutes to do the same upgrade.
Clean installs, on the other hand, were much faster, not surprisingly since no data or applications were retained. A clean 32-bit upgrade took between 27 and 39 minutes, while a clean 64-bit upgrade clocked in at between 30 and 47 minutes.
Those marks, of course, do not account for the time a user would spend restoring previously backed up data and various settings, and reinstalling applications.
Microsoft did not test Windows XP-to-Windows 7 upgrades, even though a clean install is the only upgrade path between those two operating systems. But users who start with XP and migrate to Windows 7 should expect times similar to the "clean" scenario Microsoft benchmarked. Again, those times will not include restore data and settings, or reinstalling applications; the latter can be a laborious process, with some major programs, such as Microsoft Office, taking as nearly as long as the operating system to re-install.
For clean upgrades, users -- those beginning with either Windows XP or Vista -- can use the Windows Easy Transfer utility that comes on the Windows 7 DVD to help them back up and restore settings and data.
More information about the PC configurations and user profiles that Microsoft tested, and the time trial results, can be found on Hernandez's blog.