Limit Image Sizes

I have a multi-author blog and I want to limit the size (dimensions) of images they insert (via file upload or via url) to posts. I tried the hack at http://www.techtalkz.com/blog/wordpr...wordpress.html but the style.css in atahualpa 351 was different than described in the article. Then I the Smart Image II and Max Image Control plugins without success. How can I automatically limit, resize, and/or crop photos which my authors attempt to insert into posts?