If I install a free OS replacing my Windows Vista until I can upgrade to Windows 7 will I still be able to get the $119 upgrade as long as I have my license key?

If I install another OS replacing my Windows Vista until I can upgrade to Windows 7 will I still be able to get the $119 upgrade as long as I have my license key? Or is it just a “trust” system that those who purchase just the $119 Windows 7 “Upgrade” from Vista will have had Vista? Is it simply a matter of having the license key from a Vista OS?