You can actually do this in Quicktime directly, without using Motion at all.
In QT Pro, simply go to File>Open Image Sequence, navigate to the folder that has the image sequence in it, select the 1st frame & click the 'Open' button. Then you can export the image sequence directly into the same codec that your editor is using.
Now in post: Peristroika, a film by Slava Tsukerman
Thank you Slave, I've actually done that but I thought the Motion idea was somehow ' cooler' - it's just that I am uncertain about my own ignarance when setting the parameters. Maybe I'll go back to the way you suggest.