I have to agree with Mark. That is an outstanding pic, Danalec.
I think the more you use that 50mm lens, the more glad you'll be that you decided as you did. On your 10D, the 50mm is just about the perfect focal length for a portrait lens.
In 35mm, portrait lenses are usually 80-130mm, with 80-85 the accepted standard. The 50mm lens on your 10D works out to around 80-85mm equivalent.
Keep practicing. That shot shows a great natural eye, and a good bit of talented potential.