var bulletGray = new Image();
var bulletWhite = new Image();
bulletGray.src = 'images/bullet_gray.jpg';
bulletWhite.src = 'images/bullet_white.jpg';

function bulletOver(menuItem){
	eval('document.' + menuItem).src = bulletWhite.src;
}
function bulletOut(menuItem){
	eval('document.' + menuItem).src = bulletGray.src;
}