For good performance of SQL 2005 how the server disks should be mounted in Windows 2003?

Yet another open question here, I would suggest keep the DB files on RAID 1 and OS on RAID 5, see this http://www.sql-server-performance.com/faq/raid_1_raid_5_p1.aspx and from Storage best practices notes:In order to be successful in designing and deploying storage for your SQL Server application, you need to have an understanding of your application’s IO characteristics and a basic understanding of SQL Server IO patterns. Performance monitor is the best place to capture this information for an existing application. Some of the questions you should ask yourself here are:

• What is the read vs. write ratio of the application?
• What are the typical IO rates (IO per second, MB/s & size of the IOs)? Monitor the perfmon counters:
  1. Average read bytes/sec, average write bytes/sec
  2. Reads/sec, writes/sec
  3. Disk read bytes/sec, disk write bytes/sec
  4. Average disk sec/read, average disk sec/write
  5. Average disk queue length
• How much IO is sequential in nature, and how much IO is random in nature? Is this primarily an OLTP application or a Relational Data Warehouse application?

Always place log files on RAID 1+0 (or RAID 1) disks. This provides:

• better protection from hardware failure, and
• better write performance.
  
  Note: In general RAID 1+0 will provide better throughput for write-intensive applications. The amount of performance gained will vary based on the HW vendor’s RAID implementations. Most common alternative to RAID 1+0 is RAID 5. Generally, RAID 1+0 provides better write performance than any other RAID level providing data protection, including RAID 5.