I am not absolutely certain, but my recollection is there is a 2GB max on fat32 file sizes. You won't be able to cat the pieces together except on a ext2 or a NTFS drive. I went a few rounds with this issue a year or two ago and ended up with the large file on an ext2 file and a driver to mount the ext2 file in Win2K. I was trying to get a large drive image burned to a DVD.