HI -
Create a new sequence.
Drag any one of your 1280x720 camera source clips to it. FCP will ask if you want to change the sequence settings to match the source. Say yes. Click on the clip that you just placed on the timeline and delete it. You now have an empty sequence with the proper sequence settings.
Now return to your DV timeline, and clicking anywhere on it, type Command -A to select all the clips.
Type Command - C to copy them.
Now go to the new (empty) sequence you created with the proper settings, click anywhere in it and type Command - V to paste the clips from the DV sequence.
If the video clips to not fill the canvas of your new sequence, then select all the video clips and Control - Click on any one of the selected clips. From the drop down menu choose Remove Attributes and from the Remove Attributes window that open, select the check boxes for Basic Motion and Distort and click OK.
Post back if this does not work for you.
MtD