Mach3 is widely accepted and supported software for controlling CNC machines large and small.
Converts a standard PC to a fully featured, 6-axis CNC controller
Visual Gcode display
Customizable M-Codes and Macros using VBscript
Support Windows 2000, XP, Vista, Windows 7 and 8. It is not available for MAC sorry.
If using a notebook it is recommended you use an extrenal motion controller to workaronud problems with the 64 bit parrallel port driver (click the More info button to read more on their website).
This software will be delivered by the internet - the license number will be emailed to you along with a link to the downloads. Then you install the software and drop the license key into the installation folder and you are away.