Thermistor Datasheet Reading
For anyone interested in knowing how I solved this problem, I used the AREF and 3.3V from the Arduino microcontroller connected directly one of sides of the thermistors. I believe the voltage coming out of my laptop was dropping; USB +5V was dropping to ~4.7V thus making my calculations lower.

Here's the website which helped to find my answer (this site includes CODE and DIAGRAM):

http://learn.adafruit.com/thermistor/using-a-thermistor

Thanks everyone for your help.