Edit with the best you've got. You shouldn't be "down converting" to anything until you take the final output and encode it in a Web-friendly format (I prefer QT with Sorenson Pro or the H.264 codecs).
Yeah. And if it's for the web, like Jeffy just said... You'll want a better-equipped codec than DV... and you'll likely want to drop the dimensions down to about half of DV too.