[Thruflo]

Word from a nice man at Apple I spoke to recently was to up-convert on capture and edit in Final Cut at native HD. Otherwise FCP will constantly be having to re-encode the HDV video everytime you cut between a keyframe.

That takes a snazzy capture card, eg: Decklink HD by Black Magic Design, and oodles of raid configured HDD. For which you get a happy processor (and happy H.264 should you ever choose to mature beyond 35mm and join the rest of us on the Internet).