On the contrary, there are few meaningful reasons to shoot anything but HD any more unless you're being paid by someone who specifically requests SD. Of course that's assuming you have an HD camera and HD editing software, which the original poster does. Shoot HD...

...Or, shoot HD (if not, why did you buy an HDV cam in the first place), and downconvert from the camera to SD for post. Letter-boxed 16:9 is better than native 4:3 anyway.

This way you'll have HDV masters, to re-cut later if you want. And editing in SD will create zero headaches. If you're new to the whole thing, keep it simple. 24f does look cooler than 60i but it's pretty subtle. No offense intended, but if this is your first work... you've got a lot of other things to worry about (script, direction, composition, continuity, lighting, sound, editing).

Good Luck!

Thanks everybody. That' s a lot of information. So with HD do i shoot 16:9?
So we can 't burn to HD dvd, that s why we need to downconvert to SD?