The Power Computing cases were nice, but they were just ATX form factor cases with different I/O covers. Also, FYI, the power supplies in those fry like no other. Well, not the actual power supply part, but the fan inside of them.
Standard 80mm if you were wondering as well.

I would look into the heating issue and check the P/S fan. That was the issue in the Power Computing I used for a while (never actually owned it).

Now if you want expansion, get an old server case for a dual 486 and attatch your current board in there. You could easily expand to 8 external removable bays and atleast 6 internal drive spots. The only downside is that you would probably have to go external hard drive enclosure inside and drop firewire to the drives after you run out of PCI slots.

But the clear cases are not my thing. They are okay, but they lack the comfort of grounding which I like to have. Can't afford to messup.
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MacBook 2GHz Intel Core 2 Duo w/ 2GB DDR2 RAM & 120GB SATA 5400RPM HDD
Canon Rebel XTI
Google Cr-48 Beta Laptop