2 OSes: 1 with raid and 1 without raid on ICH9R together

I don't see why not. you can use the matrix raid on your mobo to parition a portion of each drive. then create the raid 5 using those partitions. Install the OS onto the raid 5. with the other os simply install it to the non raided partition. Asumming you are using 3 drives your first OS would have 1 large drive and 3 smaller ones. the second would only see 3 smaller ones. IF you didn't want so many drives you could have the second OS create a spanned volume over the 3 partitions.