I just don't know enough about RAID controllers to comment on this. I've been looking into something like this for myself at some point down the road, but that's really a long way off for me.
Not sure that you need to spend over $100 on your motherboard for what amounts to essentially just a media server, but I don't really see anything wrong with your selection.
In my view, I'd be looking for a motherboard to house up to three PCI-Ex1 TV Tuner cards (Ceton InfiniTV4 cards) as well as a PCI-Ex4/8 slot (or x16 rated for x4 slot) for my RAID controller. I'd also be looking at a RAID controller with the RAID hardware onboard, rather than relying on the CPU for it.