Just installed the second hotfix. Seems when I try to reinstall the livery's again it says the folder already exists? Can I just rename them or should I find where they are and delete them all?

I simply deleted mine. Seems to have worked fine.

Where are they located?

FSX\SimObjects\Airplanes\PMDG 737-XXX, depending on the airplane you're installing paints for.

Thanks!