// image changer on off state
if (document.images)
	{    
	
	bioson = new Image;
	bioson.src = "/images/menu_principal_bios_on.gif";
	biosoff = new Image;
	biosoff.src = "/images/menu_principal_bios.gif";
	
	abouton = new Image;
	abouton.src = "/images/menu_about_us_on.gif";
	aboutoff = new Image;
	aboutoff.src = "/images/menu_about_us.gif";
	
	contacton = new Image;
	contacton.src = "/images/menu_contact_us_on.gif";
	contactoff = new Image;
	contactoff.src = "/images/menu_contact_us.gif";
	
	projectson = new Image;
	projectson.src = "/images/menu_current_recent_projects_on.gif";
	projectsoff = new Image;
	projectsoff.src = "/images/menu_current_recent_projects.gif";
	
	homeon = new Image;
	homeon.src = "/images/menu_home_on.gif";
	homeoff = new Image;
	homeoff.src = "/images/menu_home.gif";
	
	dirkon = new Image;
	dirkon.src = "/images/dirk_d_over.gif";
	dirkoff = new Image;
	dirkoff.src = "/images/dirk_d.gif";
	
	jefferyon = new Image;
	jefferyon.src = "/images/jeffery_j_over.gif";
	jefferyoff = new Image;
	jefferyoff.src = "/images/jeffery_j.gif";
		
      }

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

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

// Roll over for text images

// determine if browser handles image replacement

var nav = navigator.appVersion.charAt(0);
var nap = navigator.appName;
imgreplace = false;

if ((nap.indexOf('Netscape') >= 0) && (nav >= 3))
{ imgreplace = true; }
else if (nap.indexOf('Microsoft') >= 0)
{
  if (nav == 4)
  { imgreplace = true; }
  else if ((navigator.appVersion.indexOf('Mac') >= 0) && (nav == 3))
  { imgreplace = true; }
}

// prefetch images function

function prefetch()
{
  var imgs = prefetch.arguments;
  for (var i=0; i < imgs.length; i++)
  {
        tmp = new Image();
        tmp.src = imgs[i];
  }
}

// preload the following images

if (imgreplace) {
pre1 = new Image ();
pre1.src = "/images/dirk_txt_over.gif";

pre2 = new Image ();
pre2.src = "/images/willimam_txt_over.gif";

}

// image replacement functions

function img_on(srcName,imgName)
{
  if (imgreplace)
  { document.images[srcName].src =  imgName + '.gif'; }
}

function img_off(srcName)
{
  if (imgreplace)
  { document.images[srcName].src = '/images/bio_spacer.gif'; }
}