Freeware to split screen on Windows 7

[Cheetah Designs]

I would like the behavior such that I drag a window into a corner and it resize the window to predefined size, then I drag another window into another corner and it do the same so I can have 100% of my screen-estate used.

Is there a program to do this?

 

[Skeeter]

Does W7 not do this by default? Dragging to the Top Left and Top Right will make the window take 50% of the screen?

 

[MonkeyBasher]

My windows 7 does this by default.
You can have 2 windows side by side each using 50% of the screen.

 

[On Holiday]

http://windows.microsoft.com/en-gb/windows7/how-do-i-turn-snap-on-or-off

 

[Cheetah Designs]

I don't want 50/50, I want like 20/80...

 

[Threepwood]

Gridmove?