Picture resolution requirements for prints

What follows is, for more my own information than for anyone else, is a listing of common print sizes, and the approximate resolution a photo must be in order to print well and acceptably.

The math involved is to take the size of the print and multiply each side by either 300 or 200. 300 (dpi) is the best quality, while 200 (dpi) is acceptable. Armed with these two answers, you can then have a nice range of which you should shoot for. Below are the numbers found from a handful of sites.

Best: 1600x12001, 3
Lower: 1280x9603
Minimum: 540x3602; 1024 x 7684, 5
Absolute minimum: 640x4804
Best: 2048x15361, 3
Medium: 1600x12003
Minimum: 1152 x 8644, 5; 630x4502
Best: 2560x19201, 3
Medium: 2048x15363
Lower: 1600x12003
Minimum: 1600x12004; 1536x10245; 900x7202
Best: 2560x19201
Best: 3072x20481, 3
Medium: 2560x19203
Lower: 2048x15363, 5
Minimum: 1260x9902
Best: 3072x20481
Medium: 3072x20483
Lower: 2560x19203
Minimum: 2048x15365; 1620x10802
Minimum: 1800x14402
Minimum: 2700x18002

Information has been culled from Dummies (listed as 1), Walgreens (2), Samy's Camera (3), and Shutterfly (4). The Photo Company used to have information online, but I'm not finding it any more ... (hence my decision to write on this).

Edit: Found The Camera Company information (listed as 5).