function toggle_images(naam)
		{
		
			 
			if(typeof im_een == "undefined")
			{
				im_een 	= document.getElementById('een');	
				im_twee = document.getElementById('twee');
				im_drie = document.getElementById('drie');
			} 	
			
			if(naam=='een')
			{
				im_een.style.background = 'url(_site/links.jpg) no-repeat center -102px';
				im_twee.style.background = 'url(_site/midden.jpg) no-repeat center -102px';
				im_drie.style.background = 'url(_site/rechts.jpg) no-repeat center -102px';
			}
			else if(naam=='twee')
			{
				im_een.style.background = 'url(_site/links.jpg) no-repeat center -204px';
				im_twee.style.background = 'url(_site/midden.jpg) no-repeat center -204px';
				im_drie.style.background = 'url(_site/rechts.jpg) no-repeat center -204px';				
			}
			else if(naam=='drie')
			{
				im_een.style.background = 'url(_site/links.jpg) no-repeat center -306px';
				im_twee.style.background = 'url(_site/midden.jpg) no-repeat center -306px';
				im_drie.style.background = 'url(_site/rechts.jpg) no-repeat center -306px';				
			}
			else if(naam=='reset')
			{
				im_een.style.background = 'url(_site/links.jpg) no-repeat center 0px';
				im_twee.style.background = 'url(_site/midden.jpg) no-repeat center 0px';
				im_drie.style.background = 'url(_site/rechts.jpg) no-repeat center 0px';				
			}
			else
			{
				/* hoort niet uitgevoerd te worden */	
			}				
			
			
			
		}