Authoring to a DVD can be widescreen, but not at HD pixel sizes. You need to go Bluray for that. If you have to go DVD, export to MPEG2-DVD, widescreen (for NTSC that will be 720x480), and use an upscaling player.
If you are just making it for yourself, check to see if your DVD player supports any of the various HD on DVD(Divx, etc) technologies and go from there. If you are looking for a more universal solution to HD on DVDs, there is not one.