Hey,
you can adjust the sidebar and content size (select one sidebar in the options). Open up style.css and search for:
#top .fullwidth_sidebar{
width:340px;
}
and:
#content, .entry-no-pic .entry-content{
width:580px;
padding:0 0 50px 20px;
float: left;
margin:0 20px 0 0;
overflow: hidden;
}
Adjust both width values. If you increase the width value of the content area you need to decrease the width value of the sidebar area accordingly.
The tricky task is to adjust the width for all content elements - i.e the two column entries, etc. need some adjustment too:
#top .doubleentry .entry-content{
width:280px;
}
#top .doubleentry .entry{
padding-left:20px;
position: relative;
left:0 !important;
left:20px;
width:280px;
clear:none;
}
.doubleentry{
margin-left:-20px;
float: left;
clear: both;
width:600px;
}