there is no such thing as a mini-atx form factor :-s...............
The form factors (each step downwards in size mean a reduction in functionality and upgradability):
E-ATX = for servers and dual socket boards (ignore for home builds)
ATX = This is your average consumer board and what you will see in most desktops
Micro-atx = This is for the smaller desktops like the case you listed above it is still highly functional but has a limited upgradability.
Mini-itx = small size for highly portable systems same form factor as used in most laptops
nano-itx = small occasionally used in laptops but its main use in the home is as a htpc
pico-itx = about the size of the original gameboy extreme portability and only umpc's use this form factor atm
I don't see how you are getting confused it is very simple a case needs to be larger then the motherboard so that it can house it you liked the case above, so buy a micro-atx board as that is what fits in the case!!!! micro-atx is perfectly functional and can do everything a atx can except it may have lost one or two pci slots
here are some micro-atx cases pick one:
or here are some standard cases again pick one