sones the cpu and case fans spin up and are there any led glowing on the mb. this will tell you if your case power supply is good or not. (the DiabloTek ps are know to be bad and cheap). if the fan twitch you may have a working power supply but you connected something wrong or you grounded out the mb to the case. i dont know if you built any pc before but check that you used the brass standoff that came with the case. http://www.youtube.com/watch?v=rqqxqE6iswU
make sure the read case i/o shield is not shorting out the mb.
on the mb there are two power cables needed a 24 pin axt power plug and then near the cpu will be a 4 or 8 pin white atx plug.
both of these need to be connected.
the last issue is on the mb case header...if you put the power/reset/led on the wrong pins the mb wont power on. (you can take a jumper ot screw driver and tuch to two power on pin to see if the mb power on if you think your case switch has an issue.
a lot of time the cases use a cable that connects to a small board in the case and the cable is lose on the end connected to the small board.