Redgum,
When you say “Adobe Program”, do you mean the application (PrPro), or the Project? And are you saying it needs to be on its own drive, apart from the OS, media and scratch?
Also, if I put my media on my raid and preview files on another drive, does the second drive need to be as fast as the raid?
The raid transfers information at twice the speed of a normal 7200rpm drive.