I’d use a comp set to the DV widescreen preset, then switch on Pixel Aspect Ratio correction while working, just to make things look sort of normal on the computer. When it’s time to render, I’d switch off PAR correction and render the comp.
Why do you want to work in HD? Working in HD can slow you down, due to the larger image size. I’d only do it if an HD deliverable was required, now or in the near future. Since HD DVDs won’t be on the market for a while, there’s no need to create one now. Even if the TV is HD-compatible, how would you deliver the HD material? Certainly not on a DVD.
So I’d stick to DV widescreen 720×480. Use the preset.
If I’m wrong on your HD situation, please set me straight.
Steve