Sorry, can't help much with OS controlled raid. On my home/home office PC I used the raid controller on my MB because it was already there and it saved me a small amount of $ in the Windows ver. I needed.
Ironically, I have not set up raid on my newer HTPC. I may down the road but right now, I'm just using one PC to back up the other. Now I just need to update my home LAN as I am finally finding 100Mb/sec slow now that I do the occasional large data transfer. Still... not a priority.