Impact of graphics card on battery charge in this situation

[Multicore]

How much impact does a "laptop discrete graphics card" has on the "laptop battery charge" while the laptop is not used to play games ?

I will be purchasing a slim laptop or an Ultrabook (Haswell in June) - but i want maximum battery life even at the cost of a discrete graphics card.

 

[Multicore]

looks like nobody has any idea !!!