Hey Phuggan, Sean,
If you save the script text into the SwitchOrCopyFields.vbs file, make sure that the file's extension is vbs and not txt (like SwitchOrCopyFields.vbs.txt).
By default Windows hides well-known extenstions like txt, so you might see only SwitchOrCopyFields.vbs even if the file's name is SwitchOrCopyFields.vbs.txt (check the file's properties to be sure, or show the extension using menu Tools > Options > Display tab > uncheck "Hide extensions for well-known file types", or something like that).
In Notepad, to prevent it from saving with extension txt, choose Save As "All Files (*.*)" in the Save As dialog, and as file name use SwitchOrCopyFields.vbs
BTW: as this is a very old script, there might be better alternatives to do the same job (for example ExtractFields
or RegExp Find & Replace