No need for apologies MyFriend, any discussion is valued.

From Adobe....

The installation process for an upgrade requires that you enter the serial number from a qualifying product, on the same platform and for the same language version, as the upgrade product being installed.

Qualifying products go back 3 previous versions.
So I guess an upgrade from Flash 5 to Flash 8 won't be a problem, and in principle I should get my CS3 upgrade as well.

Just means I'm stuck with Windows.