//lazy way of doing it
if (document.images)
 {
   pic0on= new Image(120,32);
   pic0on.src="introHover.png";  
   pic0off= new Image(120,32);
   pic0off.src="intro.png";
   
   pic1on= new Image(120,32);
   pic1on.src="projectsHover.png";  
   pic1off= new Image(120,32);
   pic1off.src="projects.png";
   
   pic2on= new Image(120,32);
   pic2on.src="aboutHover.png";  
   pic2off= new Image(120,32);
   pic2off.src="about.png";
   
   pic3on= new Image(120,32);
   pic3on.src="resumeHover.png";  
   pic3off= new Image(120,32);
   pic3off.src="resume.png";
   
   pic4on= new Image(120,32);
   pic4on.src="linksHover.png";  
   pic4off= new Image(120,32);
   pic4off.src="links.png";
   
   pic5on= new Image(120,32);
   pic5on.src="contactHover.png";  
   pic5off= new Image(120,32);
   pic5off.src="contact.png";
 }

function lightup(imgName)
{
 if (document.images)
  {
    imgOn=eval(imgName + "on.src");
    document[imgName].src= imgOn;
  }
}

function turnoff(imgName)
{
 if (document.images)
  {
    imgOff=eval(imgName + "off.src");
    document[imgName].src= imgOff;
  }
}