With regard to the actual
How hot is too hot for a laptop
question, the
maximum internal temp
usually ranges anywhere from 140°F to 160°F, but I suppose that changes with each computer... Either way though, sounds to me like the port through which the fan dumps out the hot air might be clogged (or kind of like what reddevilggg said, it's just as probable that the cooler air from the outside is never getting all the way to the inside if the vent/intake is being blocked by... [anything]).
Do you have dogs/cats? Lots of times their hair can get sucked in through the intake and end up clogging up the exhaust vent(s)...
Just a thought. Good luck!