I would think the rsync program (which is what we used to take our data off Sun and Auspex boxen and put it *on* our filer) would be a good choice. We also use it daily to backup local data from our main data servers on to our netapp prior to moving the data to tape. It is a really good tool.
If you're using rsync, you should budget about 200 bytes of memory usage per file when copying stuff over.
Nick