I don't know of any rackmount cases but if it supports ATX, it will say somewhere in some information before you buy it.
Double check that your motherboard is ATX though. I don't know of any programs that can tell you though so you might have to open up your case, measure it then compare it to the ATX and micro ATX motherboard specs (can be found on wikipedia). Micro ATX will fit ATX cases.
On a side note you might be able to find some reviews of rackmount cases online.