Actual Computer Size Vs. Actual Print Size?

So I'm working on resizing images to enter them in a contest. When I look at them through my computer's standard photo viewer I notice that it is shrun to "best fit" but when I increase it to its actual size it comes out extremely blury. However, I am using a 14.1 mega pixel camera and when I print these images that do not turn out blury at all. I was wondering if the reason my images are comming out blury on the computer and not on paper was because the computer itself lacks the ability to show the detail on large images or if my picture "actually" look like this.