SQL Best Practices - HDD Architecture

When possible,which is not always due to financial constraints) use:

C:\ OS
E:\ SQL Binaries
R:\ TempDB (1 file per processor, equi-sized)
S:\ Data
T:\ Log


and

C:\ RAID-1
E:\ RAID-5
R:\ RAID-1 or RAID-10
S:\ RAID-5
T:\ RAID-1 or RAID-10



Working with tempdb in SQL Server 2005
http://technet.microsoft.com/en-us/library/cc966545.aspx

Storage Top 10 Best Practices
http://technet.microsoft.com/en-us/library/cc966534.aspx

Disk Partition Alignment Best Practices for SQL Server
http://msdn.microsoft.com/en-us/library/dd758814(v=sql.100).aspx