Is installing Windows 7 in-situ (on a machine running Windows already) less clean that installing at boot time?

Question

Is installing Windows 7 in-situ (on a machine running Windows already) less clean that installing at boot time?

For example - you can autorun a Windows 7 disk on a machine that is already booted up into Windows (earlier version).

Does this give a clean install (or is there an option to wipe the hard disk before the install begins?)

Answer 1

You can only upgrade from Windows Vista to Windows 7, it will not upgrade from XP.

If you insert a Windows 7 disk and run it from Windows in XP, it would require you to restart and also require you install a clean copy of Windows 7 and generally delete/overwrite the XP partition.

If done from Windows Vista, an upgrade check would be performed, and then rebooted and you are given the option to upgrade, or do a clean installation.

Generally a clean installation would be better, but upgrading shouldn't degrade performance much if at all if the system was in good working condition. Still, I always prefer a clean installation.

Update:

I tested inserting a Windows 7 DVD into my computer running Windows 7 Pro, I clicked install, it copied some files and then rebooted where I was given the option to upgrade or do a clean install. Hope that helps you.