Try this -
http://files.filefront.com/SH3_XPSP2.../fileinfo.html
Very easy to use and a readme is included.

You may have to play with the rez settings in the d3d9.cfg to get the best fit for your monitor.
Unfortunately, SH3 was not designed to be multi rez, so this is the only workaround for us. Native widescreen suport is a problem, you may experience munchkins or squashed dials. This maybe fixable if you have a nVidia card and latest control panel.