Both shots are crops from test photos taken by DPReview. Both have been scaled down to an identical pixel width and height for comparison. (Since 10 megapixels makes a "bigger" image than a 5 megapixel image, they need to be put on even ground to compare.) The 5 megapixel image has been reduced to 50% original resolution (and obviously the 10 megapixel image has been reduced by more than that). Theoretically, the 10 megapixel image should be sharper. I wanted to see the difference myself. Bicubic interpolation was used for reduction. For easier viewing, both images were then upsampled 400% using nearest neighbor to preserve per-pixel information.

The 5 megapixel image was taken by a Sony Cyber-shot DSC-717 which hit the market around September 2002.
The 10 megapixel image was taken by a Sony Cyber-shot DSC-R1 which hit the market around September 2005.

If you know of similar comparisons between resolutions, let me know. I made this page because I couldn't find others.