A DVD is always going to be standard definition. They will be 720X480.
If you want to burn a Blu-Ray, then you have the options for HD playback. There are Blu-Ray specific presets available when exporting out your movies. H.264 Blu-Ray would be the place to start. Just make sure you are using Blu-Ray media and a Blu-Ray writer.
Choose an MPEG2-DVD preset.