You're going to want to get stop-motion computer software that's compatible with your current camera or get a new camera that will work with the software. Then you can connect your camera to the computer and view your animation as your animating it. Dragon is the best software I've used but there are some other free/cheaper ones you can get.
You don't need two cameras.

Thank you for your reply but how would I know which cameras are compatible with the software?  I think I just would like to get istopmotion pro since I am using a Mac.

Since other people gave you links to stop motion software, I'll just increase the info, assuming you are willing to spend money/switch to stop motion software than just keep doing it on the camera. Visit the Dragon Frame website (http://www.dragonframe.com/) for more info on supported cameras. It's a very powerful, yet easy to use stop motion program, and it supports live view with many DSLR cameras (I've used Canon T2i and now T3i with it). I know you can get free software, but I'm not sure if any of them support live view or even support DSLR cameras. (live view is being able to see the captured image right away on the computer).