Posted 12:28AM on Sunday, July 29, 2007 Pacific Time
That's the desired order of preference when it comes to deciding on best method to generate multiple image sizes. There's a possibility imagemagick will not be installed on the server before the project commences. In any case, I've written some batch actions scripts that take most of the manual out of whipping up lean thumbnails.
In general, the formatting guidelines are as follows:
Landscape thumbnails orient to 120 px wide by 80px or 90px tall
Squarish thumbnails orient to approximately 100px on each side
Portrait thumbnails orient to 120px tall by 80px or 90px wide