I exported a Motion project to a QT file for a client in the DV format and they are unable to open it. I know they have an older version of FCP and QT so is there a way I can save it differently, maybe in Compressor?
DV hasn't changed, it is not dependent on QT or FCP versions. Most likely you exported it incorrectly, no way to tell from where I'm sitting. You can export with Compressor in any format you want to try but you don't need Compressor to give them DV.
This is my standard sigfile so do not take it personally: "For crying out loud, read the freakin' manual."