Back in 1954, Paul Fitts came up with a model of human movement which is better known as Fitts's Law.
The time required to rapidly move to a target area is a function of the distance to and the size of the target.
The edges of a computer monitor give an interesting twist to Fitts's Law in the sense that the four corners of the screen create 4 buttons of unlimited size (Just throw your mouse up there, no matter how far you move it, you will quickly have a lock on that one specific pixel).
Microsoft implemented this in Windows in for example the Close button and the Start button.
Equally, the top, bottom of the screen have unlimited height and the sides of the screen have unlimited width.
This all worked great until the invention of the multi-monitor setups. The default layout in a dual monitor setup is the "Side-by-side" layout.
This side-by-side layout is not very good as it removes all the "unlimited width" controls from one side of your main monitor and one side of your secondary monitor. In my case, I moved my secondary monitor on the left of the main monitor. If I have to hit controls which are on the left of the gui, there is no longer the "unlimited width" provided by the screen edge. It is no longer possible to quickly move my mouse in the bottom left corner and hit the start menu, clicking the controls on the left hand side of the main monitor and on the right hand side of the secondary monitor requires precision clicks.
My improvement on the "default layout" of side-by-side monitors is arranging them in a staggered fashion. The effect of this arrangement is that transition to the alternative monitor only happens via one pixel. In the beginning it requires a bit of getting used to, but after a few days it feels like second nature. The result of this setup is the loss of only 1 endless pixel on the main monitor and 1 pixel on the secondary monitor (instead of 1200 pixels on each screens). The best staggered arrangement is by putting the secondary screen on the top left or bottom right of your main monitor. This retains the easy access to the close button and the start menu.
Setting this layout on Windows 7 is done by right clicking on the desktop and selecting "Screen Resolution". On that screen you can drag the screen pictogram with the 1 and drag it above the screen with nr 2. Click OK and try it out.
I understand why this is not the default layout as the way to transition to the second screen does not feel very natural at first, but Windows should at least give a hint so people can discover that it's possible.