I use a modified version of the Silverstone LC02 case for a number of my HTPCs (other than the main theater HTPC, which is rackmount). These cases were really nice. Came with a 250w flex ATX PSU, support a full ATX motherboard, TWO PCI slots (using risers), a slim optical drive and a 3.5" HDD (or two 2.5" with an adapter). They even came with IR built in!
I wish I had bought more at the time, only bought 5. They do tend to get warm though, so ventilation is a must.
I own a current generation H5, with a riser adapter and a silent video card (Core2duo in MATX motherboard + HD6450 and power adapter in the case), which doesn't accept ATX mobos contrary to the upcoming version.