"I use Vegas. I simply choose two reference points (usually a drum beat), one at the beginning and one at the end, and then lay the new audio alongside the original audio. Don't change the original audio at all. Slide the new audio along the timeline so that the first reference points line up with each other. Zoom WAAAAY in to make sure they're precisely aligned. Now zoom back out and go to the last reference point...stretch or shrink the new audio to match the original audio...once you get the stretch/shrink point close again zoom WAAAAY in to make sure you get it exact. Now delete the audio that originally was captured with the video from the timeline, leaving only the master audio and video. Render the master audio together with the video. It's as simple as that."
I use final cut also, this is exactly how i do it. I record on an iriver h120, and in a one hour recording i am always shrinking the audio about 8 frames. Very consistent when using the same camcorder, a sony hdr hc9. Experience makes it much faster, what slows you down are the anomolies you occasionally find, many times they are errors in uploading though. I takes me between 1/2 hour and 3 hrs to sync 1 1/2 hrs of video.