I took your advice, and attemped to use iMovie with the files, but it fails to do anything.
Files must be imported into iMovie directly from the camcorder for iMovie to call the proper "Import from Camera" conversions/capture routines. Files already on your hard drive will be copied/moved to iMovie using "Import" Finder-level routines which do not convert the content to an edit compatibile compression format. So, if the files are not already edit compatible with iMovie, the import option will abort and fail when it determines the content is not edit compatible.
I will try the Quicktime component with the MPEG Streamclip.
As already mentioned by John, use of the free MPEG Streamclip app requires the $19.99 QT MPEG-2 Playback component also be installed. The advantage of this work flow is that you have the option to convert "muxed" MPEG-2/AAC fils into any QT edit compatibile compression format combination. (I would normally prefer AIC video with Uncompressed audio here, but you could also use DV/DV, DV/AIFF, Photo-JPEG/AAC, or other equally compatible combination of AV codecs.) Another free third-party option for converting "muxed" MPEG-2/AC3 content would be the free HandBrake app. The disadvantage here is that, like Lion's QT X Player, you are limited with regard to your output options—primarily H.264 video with AAC. Also be advised that QT 7 Pro, even with the QT MPEG-2 Playback component installed, will not handle AC3 audio natively.