Let's differentiate "onboard" versus "integrated." To me, something that is integrated is supported natively by the chipset (with much more bandwidth). Onboard means that there's just the functionality of a PCI card embedded on the motherboard ... and those components make use of the (typically) slower PCI bus. I would assume that SCSI and Serial-ATA RAID are onboard. While having functionality onboard is better than none at all, having that same capability natively in the chipset may be much more impressive.
-SUO