Suitable number of hard disk

Dear all,
I will buy a compaq server ml330. It will run win2003 and oracle 9i. I wish to do RAID and I will buy smart array model 641. It is capable of RAID 0, 0+1 & 5. Let say I have 3 unit 36.4gb SCSI HDD. What kind of RAID should I do ?
I would prefer an on-line standby, please advice.