I know about the board. And I know about HP. They often used ATX cases (7 slots) with Micro ATX boards (4 slots max), which does work anyway. You can mount that board in an ATX case, the power supply is standard ATX (only the physical size is different on the HP supply). Any ATX case should work and darned near any ATX power supply. Heck, you could even mount it in one of those old Gateway Convertable midtowers from the mid-90's, those were ATX and used standard size ATX power supplies.
BTW, I have a special program at <A HREF="http://www.crashmania.tk" target="_new">http://www.crashmania.tk</A> that would let you flash Asus BIOS to that board, if you can find the BIOS.
<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>