My question is, if you can't find the resultant .m2v file, how do you know Encore won't burn it properly?
You don't need to do anything special to create a widescreen DVD. Once you locate the .m2v file, just bring that (and the associated .wav file) into Encore and author as usual. The DVD will be widescreen. It will be up to the DVD (or Blu-ray) player to 'unsquish' it for display. If it appears squished, check you're player's settings.
Along with Jim's questions, why are you Exporting what appears to be HD, when doing a DVD? PrPro will be better at down-rezzing your HD material to SD, than will Encore. For even better HD to SD results, see this TUTORIAL.
I have found that the best results are from feeding Encore exactly what is needed, and not using it as an NLE, or conversion program.
The likely reason you can't find your exported file is an annoying "feature" of Premiere where it always exports to the previous export's location, even if it is another unrelated project from last week. There is no "same as project" folder setting for it as there is in the Capture panel. To find where it is, start the Export process again to get to the Export Settings panel, then click on the Output Name in gold and it will show you the current destination folder.
I'm not sure what your Encore ratio issues are. Under Preferences, Video Out Playback Settings there are 3 options for Aspect Ratio Conversion. There is also a choice for setting the DVD's menu to be 4x3 or 16x9 but that.doesn't seem to be your problem.
Check the interprete footge in Encore and make sure its set to widescreen.
In Encore you need to choose a widescreen menu to show the menu in 16:9.
--Bill, I thought I was exporting in SD from Pr by choosing the "mpeg2 dvd" format which uses 720x480
-- I found the .m2v file.but there is also an audio file and an .xmp file. do I open all of them in encore? How would anyone know to do that ?
-- the hd2sd software looks interesting but a lot of work. Is the video significantly sharper with this method?
OK, if you set your Export to SD, and have found the files, Import the M2V into Encore as a Timeline, and then Import the WAV as an Asset. From En's Project Panel, drag the WAV to the appropriate Timeline (if you have more than one), where it will snap into place. Leave the .XMP file. That should get you to authoring in Encore.
Good luck, and sorry that I missed the settings for your MPEG Export. My bad.
How would anyone know to do that ?
Read the directions. That's how anyone knows how to use any piece of software.
You know how to do something (and, even what to do) by downloading the user guide PDF for easy reading and searching
CS5 User Guides - online and PDF (see link in upper right corner at individual pages)