When it comes to hard drive storage, despite the hype about PATA, SATA and SCSI, interface is not everything. A lot of it boils down to drivers, and newer doesn't always mean better. PCBurn has done a side-by-side of a 40GB PATA vs a 40GB SATA drive
using the newest libata drivers for SATA present in the 2.6 kernel sources. Some of the results are expected, with the SATA drive getting a marginal boost, but some are quite surprising. In sustained reads, the PATA out performs the SATA drive based upon what is being read, and the SATA drive uses more CPU, at least temporarily, for the process. Against the article, the drives being compared are not identical. They have different manufacturers and have slightly different specifications. They are similar enough, however, to conclude that SATA does not always offer superior performance, though the newer libata drivers show marked improvement over the legacy IDE drivers previously used for SATA hardware. This will become more important as PATA is phased out, for both storage and optical drives.
It is difficult to give accurate benchmarks when you are dealing with equipment that varies, even though the drives in question are similar. One thing the article does show, however, is that SATA is maturing with Linux to the point of it being a perfect replacement and successor..