Set the SATA to RAID, save and exit, Enter the Intel RAID Array by pressing <CTRL+i>
Create RAID1 Array using 2 drives and then create the next RAID1 using the other 2 drives,
name the arrays so after you create the arrays you can set the correct array as primary hard disk boot device.
Boot to Windows CD/DVD, If you are installing Windows 7 or Vista the drivers are in the install disk, If you are installing XP you need to put the RAID drivers on a floppy disk or slipstream onto XP via a program like nlite.