function toggleoff() {
    if (finishedpreload) {
      if (this.src.indexOf('-over') != -1 ) {
        this.src = this.src.replace('-over','');
      }	
    }	
}

function toggleon() {
    if (finishedpreload) {
      if (this.src.indexOf('-over') == -1 ) {
          this.src = this.src.replace(/(.gif|.jpg)/,'-over$1');
      } 
    }	
}

function init_rollover() {

    if (document.getElementsByTagName) {
        allimgs = document.getElementsByTagName('img');
    
        var p = 0;    

        for (i=0; i < allimgs.length; i++) {
            if (allimgs[i].className.indexOf('rollover') != -1) {
                newsrc = allimgs[i].src; 
                newsrc = newsrc.replace('.gif','-over.gif');
              
                loadedimages[p] = new Image(1,1);
                loadedimages[p].src = newsrc;
                p++;
                
                allimgs[i].onmouseover = toggleon; 
                allimgs[i].onmouseout = toggleoff;
            } 
        }
        finishedpreload = 1;
    }
}

var finishedpreload = 0;
var loadedimages = new Array();

window.onload = init_rollover;