Do you realize I just had to go offline? (See the quick reply message )
Check your answers here http://www.cnczone.com/forums/showthread.php?t=7685
I'm not sure what you mean by a gcode interpreter. It might mean one thing to you, and a totally different thing to others. For example, to convert gcode into motion commands for a Galil controller would be a gcode interpreter to me.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)