SATA is one channel for each drive unlike IDE. I think its a step forward because the full bandwidth can be use by that drive alone. Having two drives hooked up in Master and Slave in an IDE configuration wasn't that fast in the old days, and I found I had better results when they were on seperate IDE channels.
SATA's advatage was is speed over PATA and also the fact that the drives were hot swappable. If you look you will find that SCSI is still the fastest system out there, its just expensive!