Any updates Carl?
If you want software that is easy to use, you can get paint.net as a free download, it is what I use. It is similar to windows paint the way it is set up but has features from other programs, such as, you can set a photo as the background, add a layer over the top and draw whatever you want on it, then delete the original photo from behind giving a nice clean drawing. You can even add more layers that can be moved around easily, I quite often have one layer with wheels, one layer with the frame and forks, one layer with grips and seat etc, very helpful when you want to try out different colour combinations by changing one layer at a time with the paint bucket tool.
Luke.