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I installed 1940, got the same message, opted to install the new tools, worked fine. I was upgrading from 1848 on a Mac Mini, no problems yet...
I am running Build 1848 with XP Pro and do not have any problems, even with CAD programs and microprocessor emulators, so it is working pretty...
Not to put too fine a point on it, but... From Wikipedia... History and Development FireWire is Apple Computer's name for the IEEE 1394 High...
Firewire would certainly seem useful, it is an Apple invention, after all, and is highly regarded in video editing...