The new ATA-3 standard does not provide for faster transfer modes, but improves reliability, especially at PIO Mode 4. These drives are sometimes labeled as Ultra DMA or Ultra ATA drives. The ATA-4 standard is currently being formulated. In their day, these drives were very large and fast. These drives required an ESDI controller and were not compatible with any of the previous types.
SCSI drives are also usually large and fast.
Using one will require the addition of a SCSI adapter. In the early days of SCSI, a lot of devices were made that didn't talk to each other, but those days are behind us for the most part. SCSI II is a newer standard which allows data transfer rates that are a lot higher than the older SCSI standard. SCSI and SCSI II devices should be able to coexist on a SCSI II bus. There are also Fast SCSI and Wide SCSI, two standards that allow even greater bandwidth across the SCSI bus.