function changeImages ()
{
	// arbitrary number of arguments, alternating between image name and new image file
	if ( document.images && (preloadFlag == true ) )
		{
		for ( var i=0; i<changeImages.arguments.length; i+=2 )
			{
			var imgnam = changeImages.arguments[i];
			var filnam = changeImages.arguments[i+1];
			if ( imgnam != null && filnam != null )
				{
				var img = document[imgnam];
				if ( img != null )
					{
					img.src = filnam;
					}
				}
			}
		}
}

function newImage(filnam)
{
	if ( document.images )
		{
		var rslt = new Image();
		rslt.src = filnam;
		return rslt;
		}
	else
		{
		return null;
		}
}

var preloadFlag = false;

function preloadImages ()
{
	if ( document.images )
		{
			var x1 = null;
			var x2 = null;
			x1 = newImage("#pageLevel#images/nav_pages/home_off.gif");
			x2 = newImage("#pageLevel#images/nav_pages/home_on.gif");
			
			var x_invest_1 = null;
			var x_invest_2 = null;
			x_invest_1 = newImage("#pageLevel#images/nav_pages/invest_over.jpg");
			x_invest_2 = newImage("#pageLevel#images/nav_pages/invest_down.jpg");
			
			var x_visual_1 = null;
			var x_visual_2 = null;
			x_visual_1 = newImage("#pageLevel#images/nav_pages/visual_over.jpg");
			x_visual_2 = newImage("#pageLevel#images/nav_pages/visual_down.jpg");
			
			var x_data_1 = null;
			var x_data_2 = null;
			x_data_1 = newImage("#pageLevel#images/nav_pages/data_over.jpg");
			x_data_2 = newImage("#pageLevel#images/nav_pages/data_down.jpg");
			
			var x_news_1 = null;
			var x_news_2 = null;
			x_news_1 = newImage("#pageLevel#images/nav_pages/news_over.jpg");
			x_news_2 = newImage("#pageLevel#images/nav_pages/news_down.jpg");
			
			var x_local_1 = null;
			var x_local_2 = null;
			x_local_1 = newImage("#pageLevel#images/nav_pages/local_over.jpg");
			x_local_2 = newImage("#pageLevel#images/nav_pages/local_down.jpg");
			
			var x_careers_1 = null;
			var x_careers_2 = null;
			x_careers_1 = newImage("#pageLevel#images/nav_pages/careers_over.jpg");
			x_careers_2 = newImage("#pageLevel#images/nav_pages/careers_down.jpg");
			
			var x_geosphere_1 = null;
			var x_geosphere_2 = null;
			x_geosphere_1 = newImage("#pageLevel#images/spheres/geosphere_over.jpg");
			x_geosphere_2 = newImage("#pageLevel#images/spheres/geosphere_down.jpg");
			
			var x_hydrosphere_1 = null;
			var x_hydrosphere_2 = null;
			x_hydrosphere_1 = newImage("#pageLevel#images/spheres/hydrosphere_over.jpg");
			x_hydrosphere_2 = newImage("#pageLevel#images/spheres/hydrosphere_down.jpg");
			
			var x_atmosphere_1 = null;
			var x_atmosphere_2 = null;
			x_atmosphere_1 = newImage("#pageLevel#images/spheres/atmosphere_over.jpg");
			x_atmosphere_2 = newImage("#pageLevel#images/spheres/atmosphere_down.jpg");
			
			var x_biosphere_1 = null;
			var x_biosphere_2 = null;
			x_biosphere_1 = newImage("#pageLevel#images/spheres/biosphere_over.jpg");
			x_biosphere_2 = newImage("#pageLevel#images/spheres/biosphere_down.jpg");
			
			var x_cosmosphere_1 = null;
			var x_cosmosphere_2 = null;
			x_cosmosphere_1 = newImage("#pageLevel#images/spheres/cosmosphere_over.jpg");
			x_cosmosphere_2 = newImage("#pageLevel#images/spheres/cosmosphere_down.jpg");
			
			preloadFlag = true;
		}
}