As for the cad software I believe that the German CNC conversions come with a copy of PC NC - although I might be wrong.
There's a few issues with CNC...
Basically two different types of machining to make a conponent. If all you need is a small part cut out from styrene sheet, with a few holes drilled etc, and a slot machined for example. You can use something called 2.5D Software. This is basically a 2D Drawing with the various machining steps drawn in various colours, i.e. lines drawn in red are cut using a 2mm endmill, lines in green are machined to a depth of 2mm etc. Parameters can be set for each tool, feedrate, clearance etc. You can also define the order the parts are cut so it drills the holes first and then cuts around it last.
2.5D machining is basically very similar to using a pen plotter, but rather than having different colour pens it uses different toolbits set to cut different depths of cut.
Then there is the setup to make a 3D part, from a complex 3D model created in an advanced 3D software package, like Solidworks or Rhino. These packages are very costly, and also very timeconsuming to use with a steep learning curve. The machining process is very long too, as the tool passes must be very close together to get a good finish.
The first method offers a lot more flexibility as you can normally import dxf, or dwg files from a drawing package, corel draw, macromedia flash, adobe illustrator etc. The software used by the machine will vary, but most if not all will accept the autocad drawing format.
As far as the software, I use Roland 2D Design as that came supplied with my machine and Virtual Modela for machining 3D Stuff.
The software that generates the toolpaths and runs the machine, you can use PC-NC or Mach 3. Artsofts Mach 3 is a low priced but highly capable NC controller suitable for controlling up to 6 axes.
Artsoft