Pixel Resolution for Printing

What resolution should I make my file to make a nice print?

The better questions is, how may continuous tone pixels does the image need to have to make a nice print?

According to Canon in their PIXMA photo printer series literature (Feb. 2005), you should follow these minimal guidelines.

And here is an explanation of the relationship between pixels and inches or cm.

Note that the "Resample Image" button is not checked!

If this button is checked, the number of pixels is changed and the data are irrevocably changed.  If you are making the image smaller, pixels are thrown away.  If you are making the image larger, pixels are interpolated.