judging from my stored clips, DV NTSC quicktime video is taking up around 3.6MB per second. that's 216MB a minute. i saved each one of these clips individually from within iMovie. the stored clips i have that are raw DV (from iMovie, stored in its Media folder) are 6.8MB per second (408MB a minute). quite a difference, and that's full size. not sure if FCP does anything different on this front. i've never gotten it to cooperate fully with my system while capturing.
if you were to export the entire movie at its current framerate, but scaled it down and used Sorenson or Cinepak or something, the size would be much much smaller. but it'd also take a long long time to compress (especially if it's over an hour long). you could limit the data rate to roughly 200k/sec (720MB/hour) on sorenson3, but you'd be sitting around for days while it compressed. if you're going to be given the HD anyhow, and it still has space on it, just go for a quick DV quicktime export. you can try it out on a short clip to get an idea of the size and time it'll take. if the HD is holding ALL of her files, then i don't see why you couldn't just use her FCP file and never export a thing (continue working on her FCP2 document, that is).