th.header a {
         background-image: url("../images/jquery/bg.gif"); 
         background-repeat:no-repeat;
         background-position: left center;
}

th.headerSortUp a {
         background-image: url("../images/jquery/asc.gif") !important;
         background-repeat:no-repeat;
         background-position: left center;
}

th.headerSortDown a {
         background-image: url("../images/jquery/desc.gif") !important;
         background-repeat:no-repeat;
         background-position: left center;
}