Thanks for the Information. But this quote stopped me from trying anything practically (http://arduino.cc/en/Tutorial/AnalogInputPins , Last 2nd Paragraph) :
Details and Caveats :
The analogRead command will not work correctly if a pin has been previously set to an output, so if this is the case, set it back to an input before using analogRead. Similarly if the pin has been set to HIGH as an output, the pullup resistor will be set, when switched back to an input.
Is it still OK to proceed?