help with aspect ratio and tv safe-zone for DVD slideshow

[Sprocket]

Ok, let me try an over-simplify here. I'm making a slideshow with Pinnacle Studio 8. I want it on a DVD. Studio doesn't render dvd mpeg2's with the correct aspect ratio. The way I've found around this is to render to a 640/480 uncompressed AVI and encode to 720/480 mpeg2 with TMPGEnc. Doing it this way, what do I need set the Arrange setting to? Do I need to set it to Full Screen or do I need to set it to one of the "keep aspect ratio" settings? It looks correct to me using fullscreen, but I want to make sure.

Also, what would be good dimensions to use for the Cener (custom) arrange setting to keep the video within the tv safe-zone. And going rom 640/480 to 720/480 will these dimensions have the correct aspect ratio when viewed on a TV?

thanks!