I believe the mobo model is : ASUS M52BC_M32BCIt's rare for system integrators to list the motherboard model in their specs (and Asus didn't list it), so I think you'd need to either open up the PC and physically check, or use a hardware monitor (like HWiNFO) which can read the motherboard model which should lead to the required information.
The front case panel is missingLook at the back of your pc.
If there is one expansion slot, it is ITX
If there are 4 slots, it is M-ATX.
If there are 7 slots, it is ATX.
My search says it is M-ATX.
And... why do you need a new case?