Hey Philip,
So I had a look at your site and this is a problem with your template... You will have to spend some time and modify it in a way that it doesn't screw the google map.
In this particular case the problem with the jagged edges are caused by the code in templates/MGLuxury/css/style3.css on line 197
#rt-mainbody img {
-webkit-box-shadow: #595959 0px 0px 4px;
-moz-box-shadow: #595959 0px 0px 4px;
box-shadow: #595959 0px 0px 4px;
background: #EFEFEF;
background: -webkit-gradient(linear, 0 0, 0 bottom, from(#EFEFEF), to(#c9c7c7));
background: -moz-linear-gradient(#EFEFEF, #c9c7c7);
background: linear-gradient(#EFEFEF, #c9c7c7);
-pie-background: linear-gradient(#EFEFEF, #c9c7c7);
padding:7px;
border:1px solid #a9a9a9;
position/*\**/:relative\9;
z-index/*\**/:10\9;
}
Just delete the background stuff and the popup will look as expected.
Daniel