ok but,
In XP it only asks you for a qualifying product when you do a clean install,
so you stick a cd inside for example win98 and it works...even if the win98
was in another language.
as for vista there is a trick
http://www.engadget.com/2007/01/31/clean-install-workaround-for-vista-upgrade-discovered
I know that method is not supported by ms.. just posting it out of
interest...
when I asked for a link I meant something like an eula or something saying
that you cannot do it.. because technically it is possible as long as you
do a clean install..
vista indeed is different in that it needs another OS installed even if you
wand a clean install... and that trick I posted has been around and Im sure
MS doesnt like it very much.
legally I think you can get another language... MS only cares that you have
a certain type of windows when you get the upgrade...
as long as you are not cheating ms by getting an upgrade without really
having a qualifying OS for the upgrade, what do they care?
the only problem is technical.. but as I said even that can be avoided with
clean installs.