Question : Problem: Can't install non-booting SATA RAID 1 onto new ASUS M2N-E

I'm building up a new XP-Pro desktop.  I'm booting from a SATA 400 GB drive and want to install a pair of 750 GB SATA drives as a RAID 1 Mirror set.  

In the BIOS settings I enable RAID overall, and then RAID for the two target drives.  Confirming the drives are assigned and healthy by hitting F10 in the powerup, I cannot see the RAID array once the computer finishes booting.

 When I disable the RAID in the BIOS settings and reboot, I can see the two 750GB drives.  

Would I just be better getting a PCIe card and running the RAID from it?

XP-Pro is updated.  The board BIOS firmware is current.

Answer : Problem: Can't install non-booting SATA RAID 1 onto new ASUS M2N-E

Did you check in disk management?