my $font_spec = "Dustismo_Sans";

    $my_graph->set_y_label_font($font_spec, 12);
    $my_graph->set_x_label_font($font_spec, 12);
    $my_graph->set_y_axis_font($font_spec, 10);
    $my_graph->set_x_axis_font($font_spec, 36);
    $my_graph->set_title_font($font_spec, 48);
    $my_graph->set_legend_font($font_spec, 8);
    $my_graph->set_values_font($font_spec, 8);    

##</code><code>##

uname -a  
Linux scan 2.6.26.8-57.fc8 #1 SMP Thu Dec 18 19:19:45 EST 2008 i686 i686 i386
 
This is perl, v5.8.8 built for i386-linux-thread-multi

GD-2.45
GDGraph-1.44
GDTextUtil-0.86