Go to the Mach3 folder and copy your xml file to a CD or Pen Drive etc.
The xml holds all the setting you have entered into Machs config, if you also have tools set up in the tool table you will needs to save the Tools3.dat which you will find in your macro folder then in the folder of the profile you use.
Oh meant to say the xml to save will be for the profile you are using, if its the standard mill it will be Mach3Mill.xml, if you have a custom profile then it will be your custom profile name.
Hood