HIH-4030 Humidity Sensor at 3.3 V not 5V

I'm using an HIH-4030 humidity sensor at 5 V from Sparkfun and it works fine.

I am also using a Series 2 XBee that runs at 3.3 V.
How do I change the code to work at 3.3 V instead of 5?

//#define ZeroPercentVoltage 0.8;

float val = 0;
float RH = 0;
float my_room_temperature = 70; //in degrees f !
float max_voltage = 3.27;

void setup()

void loop()
  val = analogRead(0);
  my_room_temperature = 70; // If you have temperature reading, put it here (farenhit!)
  max_voltage = (3.27-(0.00372549*my_room_temperature)); // The max voltage value drops down 0.00372549 for each degree F over 32F. The voltage at 32F is 3.27 (corrected for zero precent voltage)
  RH = ((((val/1023)*5) - 0.8)/max_voltage)*100;
  Serial.print("Relative humididty = ");

Code from previous forum. http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1267245927
Any help is appreciated. Thanks.

I guess you are supposed to linearly convert the 5V graph to 3.3V.
Not sure how to do that. Any pointers helpful. Here is the datasheet.

Examine the MAP statement