It all depends on the load your are expecting on the system.
You effectively have 6 disks to work with. You need two for a RAID 1 array for Windows and the SQL Server binaries and the page file. You may simply want to do three RAID 1 arrays. One for data files, one for log files and one for tempdb. Without knowing more about the system I can’t make a solid recommendation.
This <a href=”http://searchsqlserver.techtarget.com/tip/0,289483,sid87_gci1262122,00.html”>article</a> may help guide you.