For a server motherboard like you are planning, take a look at the Intel BOXDH61BEB3. I’m planning to use this board myself for WHS 2011 build. It should offer low power usage (as Intel-branded are generally great for this), it has 6 on-board SATA (2 SATA III), Intel NIC, 16x PCIe and 2x 1x PCIe, 2x USB3 and 2x USB2.
You could probably either go i3 or Sandy Bridge Pentium for the CPU.
Why are you going with a 650W supply? You’ll be more power-efficient with something much smaller.
