Theoretically, Serial ATA is faster--150 MB/s vs. 133 MB/s. In reality, compare RAID 0 arrays of 7200 RPM drives of IDE and Serial ATA flavor and you'll find very little difference, if any. Serial ATA drives usually have the same mechanical and electrical characteristics as their parallel counterparts, so there is going to be no perceptible difference in performance, in RAID 0 or otherwise.
im goin to get raptor, n use 80gb seagate 7200 2mb ata with abit ide=>sata converter n 80gb seagate 7200 8mb sata in raid 0. do u think single raptor will be much faster than two 80gb seagate sata(one ide to sata) in raid 0?