Are all window software keys interchangeable - language/32bit/64bit wise?

[Alishe]

If I have a key for Windows Server 2008 Enterprise and Standard 64bit - will it work with 32bit?

I know it works with windows 7 this way, just curious if it works like that way for all products?

[Cephius]

It does for the basic operating systems - I imagine the Server editions would be the same way. You're entitled to both 32 and 64 bit versions with the same key.

[kuronosan]

Does anyone know the answer to my last question? Can I use a Win7 Professional CDKey for the MS-Anytime Upgrade of Home Premium?

[Gredival]

My Windows XP x64 keys were not cross compatible with x86. When I ordered XP through my school I got separate discs with separate keys for x86 and x64. This seems to be different for Vista and 7.

[Ratatapa]

I might be wrong cuz i asked this question already but each time i try Cd with XP i got this problem.

XP version + architecture is different then vista/7

I was never able to install windows XP 64 with a 32 bits key and vise versa

and i was never able to install a Windows XP sp2 or higher with a Cd key lower aka Installing windows XP sp2 CD with a windows XP SP 1 cd key

Each time i get error saying CD key invalid, but when i use a SP 1 cd it works.

So