the transfer rate of data is a lot faster on a SATA HDD than it is on an IDE(PATA). i don't know how much of a difference it will make, i think its only if you are taking it to its limits you'll see a real difference.
It depends on the drives you use. The sustained trasnfer rate is similar for quite a few SATA and PATA drives. Some newer SATA drives are faster but the same drive on PATA would be just as fast (the interface is faster than the drive can read data off the platters)