on new request xml, old markers stay with new ones.

I have tried adding

clearOverlays();

and even the below to the function with no results

for (var i=0;i<places.length;i++) {
if (places[i].countryname>0) {
map.overlays[i].display(false);
}
}

each time i make a call to the xml request (I am not actually calling
an xml file but a php file that generates xml results) the old markers
stay with the new ones, Actually they get redrawn as the previous
shadows become darker. I have used tutorials from mike williams to get
what I have and I have made quite a few changes and I'm not sure if the
changes I have made are just sloppy or what I am missing, I am new to
the whole google maps coding and could use a little bit of advice.

here is a link... still in testing

http://rentmeavacation.com/index_gmap.php

Any ideas???