This mobo has a nice spec for the price and ASUS make quality boards.
You should note that this is a Crossfire board meaning it has two PCI-EXpress x16 slots enabling you to put two ATI vid cards in a crossfire configuration. If you only have one vid card then you only need one PCI-EX slot could save you a few quid .
This is an AM2 board so it only takes DDR2 RAM and wont take old DDR RAM, so yes it has to be DDR2 533 at the minimum.
yes your mobo will fit in your case, your mobo will come with a metal faceplate surround so that the connection ports will fit into any case!
Very nice case by the way!
__________________
Knowledge is knowing a tomato is a fruit; Wisdom is not putting it in a fruit salad
Computers are like air conditioners. They work best with windows closed.