“After a user selects ?print? from the browser, the page is formatted before it is sent to the printer. The width of the layout is reduced to about 650 pixels for 8.5″ x 11″ paper, or 630 pixels for A4, assuming normal margins.|If all the elements of a page can’t wrap around to fit within this 630-650 pixel area, content on the right will simply be cropped off. This is often caused by absolute positioning of page elements, such as fixed table widths, or large images. A web page with a fixed size of 800×600 pixels may look great online, but will lose its right edge completely when printed.|Flexible layouts relying on relative positioning are better for printing, allowing the page to compress down to fit onto paper.” James Kalbach —Printing the Web (Boxes and Arrows)
At my UWEC site I had a little PERL script that would re-format my pages for print — very helpful to me since I often taught in classrooms with no computers, so I had to print my handouts and make overhead slides. The sidebar always got cut off.
Now I’m experimenting with a CSS layout that doesn’t rely on table. The Boxes and Arrows article looks like a good starting point.