I use a 36GB Raptor and a WD 160GB SATA. The Raptor is partitioned into 2 drives, C for OS and apps, D for games and large data swaps. WD 160(E) is used for media files and safe keeping of data. I like this arrangement because it keeps stuff separate. 3D game levels load A LITTLE quicker. Probably the biggest benefit is transfers from HD to HD. I rip to the Raptor, and process and write output to E. Much, much quicker than reading and writing to the same physical drive.
RAID (not redundant) is a total waste unless you have industrial applications. The Raptors are not much faster than any good drive, and have minimal gains. Specific comparisons are available on Anandtech, Tom's, not many others I trust.
There is no IDE drive that can max out ATA-100, much less 133, by itself. Also, there is no SATA drive that can max out SATA 150, much less SATA 300 (or SATA II) by itself. As for NCQ/NCQII, and other HDD tech, little to no benefit there either.
My choice between the two is the Raptor, because it's only one drive. Lousy, actually the worst, price/GB ratio though.