Converting from bitmaps

I have some bitmap images (jpeg's) that I'd like to ultimately
convert into G-code so that I could cut them on my mill. They are
simple logo and text items. They're not gray scale-either black or a
couple of solid colors. Ideally the colors would be used to define
different depths of cut, but on a single plane.

I'm just getting started in this world of CNC, so don't know what's
out there for this sort of thing.

Thanks.
--
-Bob D.
Builder and Pilot of Kinetic Sculpture Vehicle "Killer Tomato"
Visit my web site (http://www.simpleorganicsolutions.com/tomato.html)
for pictures and additional info.