Ihave just moved over to 2007 from 2003 - The default think lines in a joined up plot is terrible - I plot huge tables .. Have anyone done a simple template with thin lines like default 2003 and no markers for each data plot ?
You can easily define a chart template and save it so that you can reuse the template next-time. Here is a tutorial on that: http://chandoo.org/wp/2009/03/10/using-excel-chart-templates/