Well the Intel southbridge has traditionally been pretty good for RAID, and ICH10R is no different. It's normally better than any 3rd party bolt-on controller.

Just be absoloutly sure that you back up often because twice the drives means twice the chance of failure, and recovering data from RAID'ed drives is an awful lot harder than doing so from a single drive (tho there is a good guide for doing so stickied at the top of this forum).