Hi, Pawel,
Usually, when you do Willingness to Pay (WTP), you use the most basic product (the one with the fewest features) as your baseline with a low price. Each line, then, is the Willingness to Pay for an "upgrade" for that feature.
The "Price Change" is what the customer is willing to pay for an upgrade, so in the attached example, you could charge $959.67 more for a larger hard drive. "New Price" is what you could charge for the whole product with the baseline settings plus that one upgrade (so, New Price - Price Change = baseline price).
The laptop example is pretty old. I'm not sure anyone would pay $950+ for a 40GB of storage these days!