What is the best way to export a movie from FCE to iDVD without losing any quality. Also, my video is widescreen, and standard definition.
First, make sure you have your chapter markers where you want them ( see below if you don't know how ).
Then, Render the whole movie.
Then:
Go to File-> Export -> Quicktime Movie
( not "Using Quicktime Conversion )
Select "Include Audio and Video"
Select "Markers: Chapert Markers"
Make sure "make movie self contained" is checked
( you actually *can* leave this unchecked, but I have experienced many bugs over the years when importing to iDVD, YMMV )
Open iDVD and select the appropriate project type ( in your case 16:9 )
Then drag the exported MOV file into the content target window in iDVD, and you're done. It will autocreate the chapter links for you. All you have to do is place them and rename them where you want them.
Here's how to create iDVD compatible chapter markers:
http://www.kenstone.net/fcp_homepage/compression_chapter_markers_stone.html
I may have missed a step there on the iDVD side, but once you get the file exported, you should be good for iDVD!
Good luck!