I've tried this a few times and I can't seem to figure out how to add a border (usually the bevel filter) to a clip or image that I've cropped. It adds the border to the entire original frame and not the cropped portion. But if I add a drop shadow in the motion tab, it recognizes the new cropped edges. Is there a setting that I'm missing? I'm using FCP 4.5 by the way. I know I could do it in photoshop, but since I don't have it on this computer, I'd have to use another in the office so I'm wondering if there's any way I can do this in FCP instead.

Move your clip up one track and resize it to whatever you want. On the track below it, insert a Color Matte of the color you want the border to be. Double click it and resize it to the dimensions that suit you.