gimp &/or xv resize function?

[paul@experimental.braille.uwo.ca]

Hi everybody, I just installed gimp and was trying to resize an image
from 640x480 to 1024x768.  I can't seem to do it.  In gimp if you use
the resize the image it resizes the window and leaves the image at
640x480.  Do you have any suggestions.  I can't seem to get this task
done.  There are no features that I can find with xv to resize an image
to a bigger size.  I have been to the gimp and xv site and could not
find the answers there.  I am not an artist just a guy trying to
customize his enlightenment desktop.

If any one can help me, I would really appreciate it and be greatful.
Paul