Once you create a QOOP poster for any set of images selecting the options you want...you generate the free preview...(without having to order the poster itself of course )
Once you get the preview image, right click to save the picture (maybe 400-600kb) onto your PC and then upload back to your flickr.com account. When you open this image (or any of our comic scans in flickr.com), click "all sizes" to show small, medium, large, or original sizes. The medium size is ~200kb or lower perfect for posting on forums.
Good luck!
GE