I didn't see this addressed in any of the recent pricing/upgrade articles or threads, so forgive me if this has been answered already. The last time I upgraded a Windows OS without performing a clean install was back in the Windows 95/98/ME era, so my opinion on the virtues of upgrading is a tad colored... I'm considering getting an upgrade license for Windows 7 because I already have a copy of Vista, but I *always* want to be able to perform a clean install. Assuming I get an upgrade license of Windows 7 instead of the full license: Do I need to have Vista installed on my machine for the Windows 7 install to work, or is having a valid Vista license key enough? What if I'm already running Windows 7 and want/need to reinstall? Do I need to temporarily put Vista back on the computer just to get the Win7 install to work? If I have a Vista install on the computer, can I opt to perform a clean Windows 7 install on a separate partition? (In other words, letting me keep a tiny Vista install on the computer just to be my "Win7 upgrade key" whenever it's needed.)

I didn't see this addressed in any of the recent pricing/upgrade articles or threads, so forgive me if this has been answered already.The last time I upgraded a Windows OS without performing a clean install was back in the Windows 95/98/ME era, so my opinion on the virtues of upgrading is a tad colored... I'm considering getting an upgrade license for Windows 7 because I already have a copy of Vista, but I *always* want to be able to perform a clean install.Assuming I get an upgrade license of Windows 7 instead of the full license:Do I need to have Vista installed on my machine for the Windows 7 install to work, or is having a valid Vista license key enough?What if I'm already running Windows 7 and want/need to reinstall? Do I need to temporarily put Vista back on the computer just to get the Win7 install to work?If I have a Vista install on the computer, can I opt to perform a clean Windows 7 install on a separate partition? (In other words, letting me keep a tiny Vista install on the computer just to be my "Win7 upgrade key" whenever it's needed.) Execellent questions! Any answers?

An upgrade license should enable you to do a clean install, just as in a XP -> Windows 7 upgrade.I assume you must have Vista installed on your machine, as the license key must be checked againstyour installation and hardware (if this were not the case, the activation could be easily transferred to any other pc, making a joke of the license).Reinstalling should be no problem if your Windows 7 version is genuine. I don't see what a rollback to Vista would add to that.The dualboot idea is interesting. It could probably work even if it violates, as a matter of principle, theoriginal concept of an "upgrade".These are my personal opinions, of course, nothing else.Mobile AMD64 3000+, VIA Apollo K8T800 chipset, 1 G RAM, ATIRadeonMobility 9700, 20x DVDRW, C:XPSP3 (55G),D:WIN7 (25G),F:DATA (250G)

djsb, This excellent Ars Technica article implies that you do need to have Vista physically installed on a drive in order to upgrade to Windows 7 - however, you could still perform a clean install if you so chose, given the necessity of the Windows XP -> Windows 7 upgrade path.-Alex