Personally i would do this...

RAID 1 = OS

RAID 1+0 = data and log

RAID 1 = tempdb

Test the above for performance. The only other option i can think of, that i would use, is below. Now a lot of people are going to throw a yellow flag here, but here me out. If you're using SAS drives then it's like having a switched network versus SCSI being more of a hub network. We have used this when we changed from a SCSI system to a SAS system. We only receieved 30% of the drives we had in the SCSI system and it performed 5 times faster. A proc went from 2 hours to 5 minutes...

RAID 1 = OS

RAID 1+0 = data, log and TempDB