Likewise. I have the same mobo range (P6X58D-E) and it just picks them up as SATA in the BIOS and in Windows, it sees it as a removable drive for some reason... even though it is set as a bootable drive from which it is booting from! I personally am using the 120GB OCZ SSD.
have you tried updating your BIOS, to be on the safe side?
perhaps you need to do some configuration in the BIOS - setting the mode to be from IDE to SATA/AHCI ?