I have a 75G in my dining room, and my home is a hundred years old, lol. The way I figure it, for a 75G or smaller, it's like setting up a huge china cabinet and filling it with china. The weight is dispersed over the whole area under the base. So you should be perfectly fine.
55G Filstar XP3 - 16" Fire Eel
75G Medium Planted - Filstar XP3 Low Light - Established Feb 2006