[support] Thumbnail resolution for CCK field

[Scott]

I would like to know where and how to set the resolution of the
thumbnail that is generated at the time of uploading an image.  The
image populates a CCK file field using the image widget.  I would like
to be able to set different resolutions for different fields within the
content type.  The particular case I'm working on is a letterhead field
that contains an image.  I have a separate theme for presentation on
handhelds and mobile phones.  I would like to use the thumbnail on those
pages but the default resolution is too small.  I'd rather not send the
full image file to a phone nor calculate resizing values for speed
reasons.

Thanks, Scott