FCP 6 is universal, that is, it works on both PowerPC and Intel. So, any FCP project cut in version 6 will work, any project cut on version 7 will not. You would have to create an OMF in FCP 7 if you want to cut it in version 6.
David Roth Weiss
David Weiss Productions, Inc.
POST-PRODUCTION WITHOUT THE USUAL INSANITY ™
EPK Colorist - UP IN THE AIR - nominated for six academy awards
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