dougs post is spot on for the max on most home outlets. all your regular outlets will be at least 15 amp but they loop a bunch of outlets together so you have to know what each device on that "loop" is pulling.
If you have a dedicated outlet with nothing else ran on it then 1500 watts is a safe guess to run off of it.
If you do not know if the outlet is "dedicated" then its a bit more confusing but i'll try.....
Most of todays electricians will put one whole room on a circuit. So every plug in that room is on the same breaker and looped together. That "room" has a total of 1500 watts to share with each outlet.
If you plug in a 1000w light then that leaves you with about 500 watts to play with , in that room. so you plug in about 4 or 500 watts of fans and other crap and your maxed out. If you were to run another light to THAT room , then you would need to plug into another room or the breaker would pop.
i hope that makes sense....im baked.