Hey Hoss - I'm (primarily) an architect and have been using CAD for many years, and have experience with a few different programs.
Autodesk products have become the industry standard, for many industries, not just the building world. I'd recommend AutoCAD LT - it's a basic 2D drafting program, I've been using it for years, and it's very powerful, yet simple to use - once you know how to use it. AutoCAD was developed many years ago for the machining and engineering industries, and has some very quirky things that have carried on through the years that are not immediately intuitive. If you've never used a CAD program before, you'd have to take a training class to learn how to use it.
I don't think SketchUp will work for what you want. It's designed to be not accurate, yet allow the user to be creative. People have done many amazing things with it, from designing new buildings, to documenting existing buildings, do designing cars, furniture, etc. I say it may not work for you because I'm not sure that it can create the type of files with the accuracy required to do CNC machine work. You can download a trial version and get * hours of use time to evaluate it.
A very good friend of mine is a machinist and engineer, and he's been using Autodesk Inventor for many, many years. He CNC's all of his own parts, and the system works great for him. Inventor is a fairly big program, and again would take some training to use. It creates 3D objects, rather than drawings in 2D (like AutoCAD LT), and the file can then be exported to a CNC to be cut. It may be bigger and more expensive than you need if you're just doing a few small parts, but it's quite impressive.
If ACAD LT or Inventor don't suite you, I'd do a little web searching for other CAD programs out there. There are many, smaller, less expensive, less involved programs that may suite your needs.