I have my doubts about put indices, data and temp on separated disks.

Let's suppose you are running a query that needs to read the data disk
intensively, the 2 other disks will be "idle".

If you create a RAID and put everything on the same volume, you will
always use the total bandwidth, no matter what kind of query you are
running. I think this case you will always have the best performance.

see you !

--
Alexandre Benson Smith
Development
THOR Software e Comercial Ltda
Santo Andre - Sao Paulo - Brazil
www.thorsoftware.com.br