btn=new Array();
btn[0]="click_.gif";
btn[1]="click_for_640.gif";
btn[2]="click_for_800.gif";
var correctwidth=800
browserName = navigator.appName;
browserVer = parseInt(navigator.appVersion);

function NoteSwap(flg){
if (browserVer >= 4 ) {
if (screen.width>=correctwidth)
document.images[flg].src=btn[2];
 }
}