I'm trying to install WinXP SP2 on Win XP Pro, but the installatiuon always
fails with "Invalid version of windows...".
The PC was bought new in a computer shop. How can I get a valid key into
the system. The PC has worked for several months so the key itself must be
valid, I guess.
What options do I have. If I can't get satisfaction from the PC shop, can I
buy an upgrade and somehow install the key from it, or do I have to
re-install?

Doug