SCSI drives are not a lot faster when working with small numbers of large files. Even the 10K drives aren't putting up better numbers than 7200RPM IDE drives. The price difference when we're talking about a DAW makes SCSI unnecessary.
SCSI is beneficial if you plan on having many drives in one system and don't want to have a bunch of IDE controllers duking it out.
RAID 0 is not really as fast as the slowest drive. In a perfect system with matched drives and a good controller, you can *almost* add the sustained transfer rates of both drives, thereby just about doubling performance. A better rule of thumb in a 2 drive system is to expect 1.5X the performance. Of course if either drive fails you're screwed.
Even RAID isn't typically necessary. 32 tracks of 24bit 96khz audio only requires ~9MB/sec sustained transfer. That's not overly stressing a well-maintained 7200RPM IDE drive.
For price and performance on a DAW, IDE is king. Now if you're running a file server or some mission critical shit, then you should be considering SCSI.
Slackmaster 2000