Windows 7 - Applocker question.

So, i'm a little confused about Applocker, I haven't really used group policy before.

Basically what i'd like to be able to do is say Windows you can't install anything to the C: drive.

On my computer C: is my OS drive anything that I install manually will go to the D:. My thinking is most viruses that you may potentially get will try to insert themselves on the C:.

Is this something that's possible?
And if so will that make lots of other things not work?

And a quick explanation of how to do this would be great.