I dont know if this will work but its worth a try :o
mount -o remount,rw /mnt/hda1
NB you will have to change the "/mnt/hda1" to reflect the partitions on your system.
You should then be able to drag-and-drop or copy the files recursively from the command line, eg:
$ cp -r /mnt/hda1/data /mnt/hdb1/destination
maybe delusional will pop up somewhere (Y)"
pinky