sargan said:
That is the bit that worries me ... I know the password for the account - but not any username or email that is linked to license.
Do you know where I can find that on the PC ?

I have this nagging worry that after upgrade will pop up a window that asks for username name and password or the email account associated with machine.

Just want to make sure I have this to hand before I do clean install.
When I go into the "User Accounts" control panel, and look at my account, it shows the email address associated with the account. Do you get the same?