Also.... dayne is right there... but you have to flush out the whole system. ie Radiator, block, heater box..
So disconnect the radiator hoes to drain it out, and also disconnect one of the heater hoeses.. Turn the heater knob to "HOT" if electrical find the heater tap in the heater hose line and manually hold it open... then stick to water hose up the heater hoses and radiator hoses and flush it out in every direction until the water is clear.
Hope you understand that... maybe :S
Any probs ... just let me know, im willing to help
Have fun... oh yea... once you have flushed it...connect the hoses back up. mix the 100% coolant to a 3rd with water..
1part coolant 2part water
and fill it up...
leave the radiator cap off, turn the car on and let it heat up (get the air buybbles out) should be right when the coolant in the radiator is hot... Just stick your finger in there... (you should know how to do that part )
Goodluck