Intel chipset, Intel Matrix RAID -> software -> driver/utility in Windows, not in your BIOS.
http://esupport.sony.com/US/perl/model- ... VGNAR730EBI looked in the marketing specifications where it says roomy 320GB harddrive (2x 160GB). This means it is already using RAID, RAID0 to be exact which increases the risk on shutdown by a factor 2, if one of the disks dies, you loose all data. Other than that, the are 15 or so notes in the text, yet only note 1 is in the folder. I do not like the looks of that either. The best thing to do is check out the manual, most likely it will explain how to activate RAID in a different way/mode (RAID1 for mirroring for safer data storage).