Well, the HAF XB fits an ATX board opposed to the 130 with a mini ITX. It's also larger and part of the HAF (High Air Flow) series. What's cool about the XB is that the tray is removable to use as a test bench as well. So for an extra $50 US, it's not bad.
It's not really classed as an HTPC type of case but it's small and portable enough compared to a Mid/Full case to be used as one.