Your kitchen floor is built to sustain a refrigerator. Your living room generally isn't. That's like comparing apples to fire trucks.
That being said, if you can go perpendicular to the floor joists, ensure no overflows (man would your downstairs neighbor be mad), and have a stand that touches the floor all the way around (versus a stand with 4 "legs") you've got a good chance that everything will be alright.
I have a 65g AGA tank/stand in my bedroom on a 2nd floor. I'm pretty sure it is perpendicular to the joists. We haven't had a problem with ours apart from the overflows onto the floor (and consequently through the kitchen ceiling)
God Bless the guy who came up with the float switch. Worth its weight in GOLD!
Join the NJ Reef Club
Today! Saving the world's reefs one living room at a time!
Atlantic City, NJ September 25-27, 2009