a: master slave?
b: separate IDE's?
Hardware RAID is better than software RAID, and SCSI is better than IDE. Unfortunately, these are also much more expensive.
If you've settled on using software IDE RAID, connect the drives to
separate IDE channels to reduce the liklihood of the IDE bus being the
bottleneck. Performance will still be bad, though, probably worse than
if you didn't configure the drives as RAID. Good luck.
This was first published in October 2001