SATA and SCSI drives with RAID to come later were initially intended for faster access to data stored on separate drives. The Raptor would be the fastest for this being that it runs at 10,000rpm over the 7,200rpm seen on other SATA drives and the newer ide drives as well. The real problem is that Windows and other applicatios are geared to run at certain speeds for the most part while you would notice some things loading faster.
One example to go by would be running XP on three different drives. The current ATA133 at 7,200, one ATA100 at 5,400, and an older ATA66 at 3,800rpm. Surprisingly the jump some time back from a 13gb 5,400rpm ide drive to a new 7,200rpm ide model wasn't noticable. The jump from an older 3,800rpm would certainly see an improvement. That is compared with 98SE as the OS installed on the three there. Now add 33% to a 7,200rpm model running XP to see some improvement and speed change noticed.