Looking for a lappy with long battery life

[PhillyDee]

As title really.
What sort of Laptop should i be looking for?
Needs XP on it.
Long Battery Life (3+ hours at least)
Not looking to spend more than 500-600 quid.
Doesnt need to be high powered, onboard basic graphics are fine.

Is it possible to calculate the approximate battery life given the wattage of the brick and the power of the battery?

 

[PhillyDee]

I was looking at an Inspiron 6400 with the 9cell battery. Was tempted to order until they clagged on £60 for postage! I think ill shop elsewhere.