[CentOS] concat mount

Hi, I've got a buffalo 1TB DriveStation run in RAID 1 mode, i.e. 500G space available, but that beast is preformatted in vfat. Buffalo doesn't recommend to run it as ext2/ext3, so I mount a vfat drive wich has the limitations "no symlinks, no uids, no gids, etc.". As I just want to use the DriveStation as a backup target, I did the following: I created files of 4G size with 'dd if=/dev/zero of=x01-backup.ext3 bs=1G count=4' (as 4GB is the maximum file size under vfat) and formatted them as ext3. I can mount them and work with them, no prob. Now I'd like to have my 25 files of 4GB file size each coherently mounted as one 100G drive. Is this possible? Must be something like Raid 0. TIA Michael