Will my motherboard fit inside this case?

That EATX motherboard is just ~3/4 inch wider than standard ATX format (10.3" vs 9.6"). The Antec 1200 is ~ 2 inches longer than the Antec 900. I'm pretty sure the 1200 can easily accommodate the extra 3/4 inch width of mobo. The mounting holes are compatible for the different ATX variants.