You can import AI files into Motion and if set right you can maintain its vector quality.
Your Illustrator file needs to be RGB and not CMYK. Be sure to save the AI file with PDF compatibility. After you bring it into Motion, just select it, press Shift+F (takes to you the Media tab), then uncheck the Fixed Resolution checkbox. This will allow the vector image to be rasterized at whatever size it is on-screen. Hope this helps.
Stephen Smith
Utah Video Productions
Check out my Motion Training DVD
Check out my Motion Tutorials