I have both After Effects and Motion on my mac. I don't know how to use either one. I have heard that both programs are similar. Am I good knowing how to use just one, or are they different enough that I should learn them both? If I shoudl learn only one, which one? I do all my editing on Final Cut if that makes any difference. I imagine Motion is built to work better with Final Cut and After Effects with Premiere, but I'm just guessing.

Paul, I can't answer your question directly, but how about this:
You can't learn both simultaneously, so why not concentrate on Motion (since it integrates with FCP), and when you can use it, you'll then be in a position to judge whether After Effects is worth learning.

For a newbie, I'd recommend Motion.. it's more intuitive looking, and easier. But not as powerful. AE is awesome.. I don't use Motion, but, if I was starting out, Motion will get your mind around the concepts of motion graphics!

Good luck - and we're all here for you and your questions.

Paul, I have both, tried both, settled on After Effects and never looked back. The basic idea of Motion, to use behaviors instead of keyframes, is cute on paper but, IMHO, it makes you spend more time trying to fine tune the behavior than simply drag the keyframe around. Also, AE keyframe controls are just superlative and make the job easy and intuitive.
For examples of professional and stunning work done in After Effects see John Dickinson's site: http://www.motionworks.com.au/
Very informative and full with tutorials that can get you started in no time there is also the excellent http://www.videocopilot.net

After having spent a few years with AfterEffects I can't say enough about the product, to me it's the essential addition to any NLE. If you need integration with FCP, my editor of choice, you can use several approaches. There is a new AE script that recognizes automatically the cuts and creates the AE layers for you: http://aescripts.com/2008/01/18/magnum-the-edit-detector/ (Magnum the edit detector)
There's also one that will read a FCP sequence exported with XML and create the corresponding AE composition: http://aescripts.com/2008/01/18/magnum-the-edit-detector/

These two scripts also introduce an important topic if you are going to invest time learning compositing: AE has dominance of the plugin market. If you will need something to get the job done you will be more likely to find it for After Effects than for Motion. Several plugins have been adapted to work on both hosts but not many.

Good luck.

I know after effects, and was able to figure out motion very quickly. But I haven't found any reason to use motion over after effects. As someone else pointed out, motion maybe better to start with, but if I had to choose one over the other it's after effects.

thanks everyone, especially Paolo, for your input. I'm going to go with AE since it appears to be the superior program