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#11
I would personally advise that you remove the existing version and install the version that came with the key you intend to use. Either way should work equally well but experience teaches that a totally fresh install is more stable over time.
as for the best method of removal either the built-in or the Revo method is viable though the built-in method may need some manual tweaking. Historically, the windows uninstaller is conservative in it's action, keeping any .DLL or registry entry that may be needed by other applications, Revo and other third are more aggressive so can do the job without the manual tweaks.