Fedora :: How To Best Replicate Dying Hard Disk?

I'm pretty sure the hard disk on my FC5 system (tells you how old it is!) is failing. It's a 500GB drive and I have a second hard disk that's 1.5TB (if I remember right) as a secondary.I would like to (ideally) just migrate everything -- settings, MBR, OS, home dirs, etc., everything -- to a different drive, take out the one that's on the fritz, and reboot the system with everything as it was...just a new hard drive.

Alternatively, I figure I could remove the old drive, move the secondary one into place as the primary, reformat it (assuming there's no data I need), and then install a fresh FC version and from there, migrate data from the old one as needed. I've done this latter method before and assuming the hard drive doesn't totally go, it should work. But I'd really RATHER have somehow a "mirror copy" of the 500GB drive that just seamlessly replaces what's currently there.