The machine settings are stored within the 'Mach3Mill.xml' file (or whatever profile you are using .xml). The screen specific stuff is stored in '1024.set' (or whatever screen you are using) and the Macros folder contains any macro's you use. Also don't forget to save your license file (Mach1Lic.dat). That is the basic stuff but be cautious because you may have more Tormach specific files stored elsewhere so don't delete anything or make any changes you cannot reverse. (This is really the reason I suggested the additional HD you could install the latest version of Mach3, copy over the files mentioned above, then make any changes you choose).
Thanks for the complements relating to the laser project, I am hopeful more will follow.
I believe that one day everybody with a CNC will have a laser attached (probably fibre rather than CO2) but it is a bit slow catching on at the moment.
Tweakie.