We are having a little coffution with QuickTime and hope that it is only something that QuickTime does and not a Final Cut problem. We ussually work with 19 bit uncompressed material and never had any problems exporting uncompressed QuickTime files. But recently I found out that after exporting an uncompressed proyect the info on the file indicates a 640 x 480 file instead of the 720 x 486 correct dimentions.

Our forkflow is at folows:
If the material comes from a DigiBeta, we transfer it at a dub house. If not we captured ourself. All material is captured at 10 bit uncompressed.
We create an uncomprresed 10 bit sequence and work on the proyect normaly. Since the file and the timeline have the same settings, there is no need ti render.

Once the project is finished we export with current settings. This creates a new uncompresed QuickTime file. This is the file that has the wrong dimentions while playing with QuickTime X.

It seems that is only a Quicktime issue because if you bring it back to Final Cut Pro it will show withe right dimentions.