HiTweekie, I used DeskCNC, although there are other readily available softwares that will convert BMP to Gcode. You need to massage the grey scale image to get the best results for the lettering. Just take the BMP and make the image as contrasty as possible, sharpen up the edges etc, there are several choices of photo packages to do this. Once the image is processed then you just pass it to DesckCNC and set the parameters. With really small cutters I found that exceeding 0.003' depth is asking for trouble, so take more than one pass if you want more depth. When I did the plaque I had my machine as tight as possible with back lash <0.002 so if you have good ball screws and no backlash you're in business. I had cheap all thread 1/2" X 20. My table runs on linear bearings.
If you look at the "Golden wedding anniversary gift" topic you can see 3d relief images done also using DeskCNC.
Mike