emusonacid! legacy

Hi,
I have done this before and don't seem to understand the problem. I am trying to take sounds from my external scsi (formatted 4.7 Fat 32) to my Hitachi Travelstar internal ide Hard drive also formatted 4.7 fat 32. When I try and back up my sounds it says device full. I just did this with another hitachi Travelstar and had no problems. It makes no sense. I am just switching out the hard drives, formating them and trying to save.

Does anyone have any idea what the problem is?
thanks