A lot of the new mobo's handle the SATA drive by making it appear as a PATA drive to the OS. That way it's easy and there is no need to install software drivers for the new interface. Don't worry about "dumbing down" - this technique does not appear to harm the speed or capabilities.
When I set up my system I configured for AHCI in BIOS, but then Win XP Pro could not find the drive to install onto. I used the utility CD that come with my Seagate drive to partition and format my drives, but that software did not allow me to exceed the 137 GB barrier because it had no knowledge of the OS to come. The XP still could not install. Eventually I switched off AHCI and presto! XP installed just fine. Then I had to play around to re-partition to full HDD capacity in one volume.
Maybe I just missed out on the proper way to get XP to recognize an AHCI drive during install.
SATA does not need RAID, as you suspect. I found some mobo manuals spend so much time explaining the special needs of RAIDs that it is hard to find how to not do that and just go the plain-Jane route.