Never migrate applications...alway install from scratch.
Yeah, you can install without losing project. Back up the project file, perhaps onto the drive with your media...then erase and install the OS, then FCP.
Man, FCP needs an uninstaller. Oh, try this one:
[
www.digitalrebellion.com]
www.shanerosseditor.com
Listen to THE EDIT BAY Podcast on iTunes
[
itunes.apple.com]