I found this on the Asus website. And will answer your question;
Intel is the world's first chipset maker to integrate Serial ATA (SATA) and RAID 0, 1 functions into the South Bridge. The latest ICH5R chipset now delivers 150MB/s fast data transfer (SATA) and striping performance to enhance computing efficiency.
Your friendly neighborhood PC tech
Source:
http://usa.asus.com/products.aspx?l1...78&modelmenu=1