for me it was the opposite ...
I normally wouldn't qualify for a "free" (25 euro S&H LOL) vista upgrade, as I bought my vaio like 4-5 weeks too soon.
I registered for the upgrade, filled out a purchase date that would qualify me for a vista upgrade and finished the registration with my cc-info.
Then I got the instructions to mail/fax a copy of my invoice and that after they got it they'd charge my cc and send me the upgrade.
I didn't send them anything, but like 2 months later the vista upgrade was in my mailbox
