Honestly, I think everyone here is missing a very important step, especially for someone who is not sure of the decision.
1-boot linux via usb to try
or the like, make an image of your disk
Now, continue with partitioning and whatnot. If you ever want to go back to this point, you have a myHardDisk.image to go back to.
EDIT: I misread. The person above me got the whole cloning step.