The F key is match frame and brings up the clip in the browser. Cmd-Opt-F matches back to a new copy of the media. Shift-F shows the location of the clip in the browser. Control-click on the clip and you also have a Reveal in Finder function. Take your pick.
All the best,
Class on Demand DVDs "Complete Training for FCP7," "Basic Training for FCS" and "Final Cut Express Made Easy"
Author: "Final Cut Pro 5 Editing Essentials" and "Final Cut Express 4 Editing Workshop"