Digital Photo Resizing Bleg – Part II:

Thanks to all who responded to my bleg on digital photo resizing. Pursuing one of the suggestions offered by commenters, I have downloaded a digital photo resizing program. Unfortunately, the resizing options are listed in terms of pixels rather than inches (i.e. -640×480 pixels instead of 4×6 inches). My question for you experts out there (or just those whose ignorance is less profound then mine): What pixel option should I choose to resize digital 4.5×6 photos to the standard 4×6, so I can then print them out in 4×6 size without cropping (my original objective)?