Looking for the detailed analogRead information

Hi, Im using Arduino Diecimila, there is 5 analog In ports that i need to monitor. I have IR distance sensors connected to them, the output on this sensor is 0-3 V. As i have read that Arduino has range 0-5 V and function analogRead will send back integer -1024 .. 1024. What i need to know is table of conversion : Example 2.456 V in will give me via analogRead() = 2.456 / (5/1024) = 502

Is my information correct? or it uses long?

The Analog to digital converter has 10 bit of resolution so it will give you a value in the 0 - 1023 range for a voltage in the 0 - 5V range.

each value represents aprox. 4.88 mV ( 5000 / 1024)

But you can change the reference voltage for the ADC so you can get the full 0 - 1023 range to match 0 - 3 Volts