Ooh, I got an Antec P160 - very nice case! But I had a similar problem with my CoolerMaster Aerogate 2 cos it only has two small holes for mounting and the thing is 1/3 the depth of a CD ROM drive.
If you're gonna change your res then go for the cylindrical Danger Den res. It's got a neat little cap for filling and a block inside it to stop bubbles going in to the loop if you have a high power pump. Very handy
