Oh boy, HD probs - i think.

[Black]

I would absolutely install the clone after verifying the disk once zeroed/reformatted.
If the disk comes up clean after reformatting, there's no reason in the world not to go with the clone, unless you enjoy spending hours needlessly futzing with your mac.

RAMd®d wrote:
If you reformat, your HD will be erased in the process, one step.

You can reformat and zero the HD in one step by selection Options or Security (not in front of Disk Utility at the moment) and something like Write once and then start the process. This will take a while so you might want to put on a French maid uniform and engage somebody in a pillow fight while bouncing on a bed.

Your HD will be erased, bad blocks (if any) mapped out, formatted (HFS+) and ready for your OS Install.

Now at this point, I'd install the OS and apps from scratch. Cloning your HD and installing it on your much faster external HD defragmented your OS, (although X can handle a lot of fragmentation). But your OS may still have sustained damage/corruption over the years, and freshening it up is a good idea.

If you're curious, you can reinstall the clone to see if it will now work. Me, I'd just skip that step and install anew.

Then, after you install your new OS and it's working fine, repair permissions. You might even want to Verify your HD. And finally, I'd boot from the external and run Disk Warrior on your internal HD.