if (document.images) {
	var img = new Array();
	//enter images into the array
	img[0] = 'images/nav_home_0.gif';
	img[1] = 'images/nav_home_1.gif';
	img[2] = 'images/nav_location_0.gif';
	img[3] = 'images/nav_location_1.gif';
	img[4] = 'images/nav_expertise_0.gif';
	img[5] = 'images/nav_expertise_1.gif';
	img[6] = 'images/nav_advantages_0.gif';
	img[7] = 'images/nav_advantages_1.gif';
	img[8] = 'images/nav_surgery_0.gif';
	img[9] = 'images/nav_surgery_1.gif';
	img[10] = 'images/nav_resources_0.gif';
	img[11] = 'images/nav_resources_1.gif';
	img[12] = 'images/nav_news_0.gif';
	img[13] = 'images/nav_news_1.gif';
	img[14] = 'images/nav_employment_0.gif';
	img[15] = 'images/nav_employment_1.gif';
	img[20] = 'images/nav_anesthesiology_0.gif';
	img[21] = 'images/nav_anesthesiology_1.gif';
	img[22] = 'images/nav_plastic_0.gif';
	img[23] = 'images/nav_plastic_1.gif';
	img[24] = 'images/nav_general_0.gif';
	img[25] = 'images/nav_general_1.gif';
	img[26] = 'images/nav_gynecology_0.gif';
	img[27] = 'images/nav_gynecology_1.gif';
	img[28] = 'images/nav_ophthalmology_0.gif';
	img[29] = 'images/nav_ophthalmology_1.gif';
	img[30] = 'images/nav_orthopaedics_0.gif';
	img[31] = 'images/nav_orthopaedics_1.gif';
	img[32] = 'images/nav_pain_0.gif';
	img[33] = 'images/nav_pain_1.gif';
	img[34] = 'images/nav_urology_0.gif';
	img[35] = 'images/nav_urology_1.gif';
	img[36] = 'images/nav_ent_0.gif';
	img[37] = 'images/nav_ent_1.gif';
	img[38] = 'images/nav_podiatry_0.gif';
	img[39] = 'images/nav_podiatry_1.gif';
	img[40] = 'images/nav_physicians_0.gif';
	img[41] = 'images/nav_physicians_1.gif';
	img[42] = 'images/nav_oral_0.gif';
	img[43] = 'images/nav_oral_1.gif';
				
	var im = new Array();
	
	for (var i = 0; i < img.length; i++) {
		im[i] = new Image();
		im[i].src = img[i];	
	}
}

function toggleImg(imageName, num) {
	if (document.images) {
		document.images[imageName].src = im[num].src;
	}
}