I thought I'd already covered this. Anyway, many folks moving from iMovie to FCE would like a way to destructively edit as per iMovie 4. Some of the reasons maybe that they haven't got time to to sit with the camera/tape deck and log all the footage (It's certainly quicker scrubbing through footage on a hard drive than it is on tape) and/or they'd prefer to do a straight long import to reduce wear and tear on the camera mechanism.

The best way to destructively edit is to set your editor preference to Quicktime Pro in FCE. You can then right click on the captured media clip in the browser and select "Open in Editor". This will open the actual media from your scratch disk in Quicktime Pro. Any edits made there will be destructive. I.e. trimming footage from the start or finish. You could even split clips up, etc, all retaining the timecode information making for safe re-capturing. Simple, but effective