Motion lines!

I am trying to export my SD project (DVPRO-NTSC, 29.97 frame rate, frame size 720x480) from Final Cut Pro 6 to Compressor 3.0.5. However, in both the preview window in Compressor and the final compressed product (in this case a MPEG2 file using 'Best quality 90 mins DVD') I get motion lines. They are really noticeable in the credits which use the typewriter effect, but can be seen the in the whole movie whenever something moves. They small horizontal lines that appear at the edges of the moving objects. In Final Cut, my project is set for 'Field Dominance: Lower (even)' and in Compressor my inspector window shows 'Native field dominance: bottom first' so i think they should be compatible.
The weird thing is that when I export my project to a quicktime movie file it plays back fine, with no motion problems. I haven't tried burning the Compressed file to DVD yet so I can check it out on something other than my computer, cuz I here that can be the problem.
Also, Compressor previews my 16x9 movie as 4x3, is there any way to change that too?
Thanks for the help! Let me know if you need more info.

David