Notes:

1. The reference is to a table in Digital Camera Solutions by Gregory Georges, p 24. This table shows, for example, that a 1.0 megapixel camera with a pixel width of 1152 pixels will produce a "photo quality print" 10.0 inches wide. That is only 115 DPI (dots per inch). This seems a little sparse to me.
2. Generally printers print at 300 DPI which would produce a print width of 3.8 inches (see table), a very small print for a 1.0 megapixel camera. Others have made recommendations for 150 and 200-250 DPI.
3. Perhaps a compromise should be taken at 200 DPI, which would give an acceptable print of 4x6 inches for 1.0 megapixels. Whatever size print is used the final result should be acceptable to the viewer.
4. Search google for 'Genuine Fractals' for a method of improving your photos for large prints.