This is a Textbox module. This is the CSS I used:

.xg_widget_main #xg_layout_column_1 { display:none; }
.xg_widget_main #xg_layout_column_2 { width:740px; }

Note that because this is a CSS hack, the Members box and other modules like photos may not stretch automatically to how you want it to look. The left column still exists in the HTML, but we just use CSS so that it appears to be hidden. We also use CSS to stretch out this middle column to 740 pixels.

There is a way to display member icons and photo and video thumbnails so that they stretch the width of a module with another caveat - Ning displays items in particular multiples. If you can live with that, you'll be okay.

.clist { display:inline; }