if (document.images) {

// pre-cache all 'off' button images

var offImgArray = new Array ()
offImgArray["home"] = new Image(92,25)
offImgArray["services"] = new Image(116,25)
offImgArray["contact"] = new Image(123,25)
offImgArray["links"] = new Image(102,25)

// off image array -- set 'off' image path for each button
offImgArray["home"].src = "images/nav_home.gif"
offImgArray["services"].src = "images/nav_services.gif"
offImgArray["contact"].src = "images/nav_contact.gif"
offImgArray["links"].src = "images/nav_links.gif"

// pre-cache all 'on' button images
var onImgArray = new Array ()
onImgArray["home"] = new Image(92,25)
onImgArray["services"] = new Image(116,25)
onImgArray["contact"] = new Image(123,25)
onImgArray["links"] = new Image(102,25)

// off image array -- set 'on' image path for each button
onImgArray["home"].src = "images/nav_home_on.gif"
onImgArray["services"].src = "images/nav_services_on.gif"
onImgArray["contact"].src = "images/nav_contact_on.gif"
onImgArray["links"].src = "images/nav_links_on.gif"
}

//functions that swap images 
function imageOn (imgName) {
	if (document.images) {
		document.images[imgName].src = onImgArray[imgName].src
	}
}		
function imageOff (imgName) {
	if (document.images) {
		document.images[imgName].src = offImgArray[imgName].src
		}
}