Any external SCSI II hard drive will work as long as you limit the partition sizes to 4 gig. It is reccomended that you get harddrives that have the same (or better) performance characteristics as the Quantum Fireball IDE drive that is internal to the 788. Check the specs on the 788. Also you can increase the size of the internal IDE drive to a max of 16 gigs. The 788 can have no more than 4-4gig partitions per drive and no more than 7 drives on the SCSI chain. The cdr-788 and internal SCSI controller already consume 2 of the 7 possible.