var pic ="";


var smallPic ='<img src="pics/Crane/crane0131S150x112.jpg" width="100" height="75"  alt="Remove Trees With Crane" /></a>';
var largePic ='<img src="pics/Crane/crane0131S150x112.jpg" width="150" height="112" alt="Remove Trees With Crane" /></a>';


if (screen.width > 800)
  pic = largePic
else
  pic = smallPic;
  

document.write(pic);