I'm rather new to CS4 and I 'm finally going to HD.
Is there a set rule, as far a quality is concerned, that says I should edit in HD and then export the whole project to SD for DVD?? Or since I have an excellent HD toSD converter, can I just convert my HD and do all my editing in SD ?? Which is generally considered the best option?
Thanks

Editing in HD will give you the option of easily outputing HD versions in the future if the need arises. If your editing system can handle it, I would highly recommend editing in HD. Fewer issues with interlacing nd pixel aspect ration, especially for outputs being scaled for the web. SD deliverable will always have those issues to contend with, no matter what format you edit in.

Personally, i would edit in HD, but you haven't indicated your source material.

If your HD footage is shot progressive, then CS4 does a fine job of rescaling for SD output..

If the HD footage is interlaced, then you're going to have a bit of trouble doing downconverts..
There is no magic button...

But like Mike says....At least you'll have everything in HD for future proofing..
Before you know it, BluRay will be the standard.

What is this excellent HD to SD converter that you have?

Thanks Mike and Peter........ It always helps to get good suggestions with logical explanations..

Peter, Your note about shooting HD progressive helps too. Everything I've shot so far has been interlaced.
Glad to know CS4 does a better job with progressive. I'll try that for sure.
Also, to answer your question, I've found TMPG Enc 4.0 Express seems to be noticably better than all the other's I've tried. Of course it's more expensive, but seems to be worth it.

After Effects can scale interlace ffootage properly, but I have not gotten as good of a result with Premiere/AME. It may have improved in CS5, or maybe i don't have the settings right, but I have always gone to AE for maximum interlacing and pulldown quality.

I would strongly recommend editing in HD.
In the early HD days I did several big projects shot in HD, edited in SD, delivered in SD.
Now, I really regret not having HD masters of the final cuts.
If you edit in SD, there is no easy way to go back.If you have an HD master, you can go anywhere you'll ever need to with it.
It's "future proofed"