Polaris GPS

I am trying to save myself looking on the Polaris website, hoping someone here may have one and know what to do.

Mate got one of these Polaris DG7700 units through 4WD Action and in their offroad wisdom they sent a unit with no offroad loaded. It says it takes Oziexplorer also, my question is, does anyone know how to load it to this unit, I have a copy and some maps he can use, just need to know if its as easy as copy to the memory stick and run it? Also the next problem, in the talking map, is there anyway you can increase the volume in the talking map so it can be heard over the stereo system, I have increased volume in the talking the map, to maximum, but it is still hard to hear?

Any help would be great..

Cheers