function Is() {
   var agent = navigator.userAgent.toLowerCase();
   var version = navigator.appVersion;
   this.major = parseInt(version);
   this.minor = parseFloat(version); 
   this.ns = ( (agent.indexOf('mozilla')!=-1) && ((agent.indexOf('spoofer')==-1) && (agent.indexOf('compatible') == -1)));
   this.ns2 = (this.ns && (this.major == 3));
   this.ns3 = (this.ns && (this.major == 3));
   this.ns4b = (this.ns && (this.minor < 4.04));
   this.ns4 = (this.ns && (this.major >= 4));
   this.ns405 = (this.ns && (this.minor >= 4.05));
   this.ns407 = (this.ns && (this.minor == 4.07));
   this.ns408 = (this.ns && (this.minor == 4.08));
   this.ns45 = (this.ns && (this.minor == 4.5));
   this.ie = (agent.indexOf("msie") != -1);
   this.ie3 = (this.ie && (this.major == 2));
   this.ie4 = (this.ie && (this.major >= 4));
   this.op3 = (agent.indexOf("opera") != -1);
   this.win = (agent.indexOf("win")!=-1);
   this.mac = (agent.indexOf("mac")!=-1);
   this.unix = (agent.indexOf("x11")!=-1);
}
var is = new Is();
var coolBrowser = ( is.ns4 || is.ie4 );

function swapImg ( name ) {
  if ( coolBrowser && document[name] ) {
    document[name].src = eval(name + "OvrImg.src");
  }
}

function restoreImg ( name ) {
  if ( coolBrowser && document[name] ) {
    document[name].src = eval(name + "OutImg.src");
  }
}