Keep in mind that by default, QT files are created with a 'medium' quality playback setting. You can turn on the high quality playback flag using the following method:
1-Open the file in QuickTime Player (pro).
2-Hit Command j to open the movie information window
3-Select "Video Track" from the left drop down menu
4-Select "Quality" from the right drop down menu
5-Check "High" from the choices.
The QT file should now look better on your computer monitor (but still stretched)
You can do the same as above by downloading and using the drop-n-drag application "HiQual":
http://www.versiontracker.com/dyn/moreinfo/macosx/14255
Also remember that although your footage may not look all that great on your computer monitor, it isn't a good indication of how it will look when viewed on an external TV monitor.
-DH