If you disconnect the electrical connector going to your passenger seatbelt assembly, you will get this light on your dash. I'm not sure about the driver's side, but I would assume the same for there too.
Check to make sure that connector is secure, as well as the wires that go into both halves. This connector is for the pyrotech device in your seatbelt and if its not hooked up, it gives that "airbag" alarm.
I have an aftermarket seatbelt on the passenger side and this light is lit on my dash all the time as there is not pyro device in my aftermarket seatbelt. I have not figured out if you can jumper the plug or insert a resistor anywhere to "cheat" the dash light. I'm afraid to just arbitrarily try something for fear of shorting out the computer or something.
Hope this helps.
"The World was large, now it is small. It was lonely, now it is crowded. It was dark, now the lights are on. Some day the old will be new again. Keep your guns close but your sword closer. For one day Man will again fear the dark of the World."
--The Zombie Prophet