Scrolling

Hey, I wonder if someone can help me.

I want to do something but I have no idea where to start.
Mouses have a scrolling function(up and down). Unfortunately I don't have a mouse on my netbook. I know there is a function to scroll with the touchpad but I would like to do something else.

I want to assign the scroll up function (and the scroll down) to a specific key on my keyboard. I know that the arrows can do that on websites for example but it is not the scroll up function of the mouse.

Is there a way to do this? Is there a registry value or something to help me do that?
In other words I want to be able to press a keyboard button which will use exactly the scroll function of the mouse.

Thanks in advance.