function bw_check(){
   var is_major = parseInt(navigator.appVersion);
   this.ver=navigator.appVersion;
   this.agent=navigator.userAgent;
   this.dom=document.getElementById?1:0;
   this.opera=this.agent.indexOf("Opera")>-1;
   this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom && !this.opera)?1:0;
   this.ie6=(this.ver.indexOf("MSIE 6")>-1 && this.dom && !this.opera)?1:0;
   this.ie4=(document.all && !this.dom && !this.opera)?1:0;
   this.ie=this.ie4||this.ie5||this.ie6;
   this.mac=this.agent.indexOf("Mac")>-1;
   this.ns6=(this.dom && parseInt(this.ver) >= 5) ?1:0;
   this.ie3 = (this.ver.indexOf("MSIE") && (is_major < 4));
   this.hotjava = (this.agent.toLowerCase().indexOf('hotjava') != -1)? 1:0;
   this.ns4=(document.layers && !this.dom && !this.hotjava)?1:0;
   this.bw=(this.ie6 || this.ie5 || this.ie4 || this.ns4 || this.ns6 || this.opera);
   this.ver3 = (this.hotjava || this.ie3);
   return this;
}