images

Hi,
I have a small problem with usage of the images. I have a column which contains images along with text. when am clicking on the column header am getting the column sorted based on the images. am getting these images which are stored in jpg format. Eg: I have a columm contaning the doc, pdf, xml, ppt,...... when am clicking on the column header am getting the column sorted with the following order ppt, doc, pdf, xml,...
could it be possible for me to have the sorting as doc, pdf, ppt, xml,....
(am using version1).