we needto set a maximum of 640x480 for the images linked fro

Hello, we installed a fck editor in drupal 6.2, and we want to set a maximum of 640x480 for the images linked from internet, and, when the image linked is biggest than 640x480, the editor made a auto resize.

how to do it?

Please we need help!

Thank you very much for any suggestion!!

Regards,
Marcelo and Esteban.-