I don't think I could do much better than ChrisDesign yet wanted to point out that this is a very low resolution image as if taken by a 2 Mpixel camera. You would have a much better result if you had a higher resolution image as a starting point or if this is a print, having it scanned at a much higher resolution. If you cold only post this image due to size limitations, it would be better to post the image on a sharing site and provide the link to the higher resolution image. If that is a possibility I am sure it would be amazingly better results.
Just a suggestion.