For cases, this is probably my favorite. Or rather, THESE are my favorites.
Big, easy to build in, cools amazingly, and cheap. And steel. And awesome on the whole. Bit on the loud end, but the inside runs cold with my friend's rig that has a Q6600 Thermaltake v1), an 8800GTX, and 2 gigs of RAM. Also, it lights up like a Christmas tree if you have all the LEDs on.
EDIT: One caveat: You DO have to buy an additional 120mm fan for the front if you want one, the case on its own doesn't come with one.