Server build notes
don't use the onboard sata ports. for now, I like the sata_sil parts, as they support hotswap, and are pretty cheap. Most of my boards only have one pcie slot so that is hard. 4x500G drives is better (striped mirror) but 2x1000g is fine.
tyan thunder n3600r
(super cheap if you can find it, but only because it isn't sopposed to work. will cause support hassles. But I have spares. supports quad-rank ram)
(more expensive, slightly better supported by DMIDECODE, max out at 64GiB ram, no quad-rank, everything 'officially works') KVR533D2E4K2/4G KVR667D2E5K2/4G KVR533D2D4R4K2/8G KVR667D2D4P5K2/8G
I like the supermicro 833... I found a bunch of http://supermicro.com/products/chassis/3U/833/SC833T-550.cfm for cheap, so I use those often. If you need fewer than 4 drives, though, a 1u gives you a lot more flexibility (many places charge extra for hosting a 3u)