The paths only are required if you are elected to use ImageMagick
If you are using gd2 then they can be blank
But anyway the path I got for ImageMagick from express was
/usr/bin/convert
/usr/bin/mogrify
But as stated you really should call Tom to confirm.
BTW,
The areas that have a option to use one or the other are:
Control Panel » Gallery Settings
Control Panel » Display Options[-] Post/Reply Page Options
