res = new Image();
res.src = "images/nav_res.jpg";
res_m = new Image();
res_m.src = "images/nav_res_roll.jpg";
constr = new Image();
constr.src = "images/nav_new.jpg";
constr_m = new Image();
constr_m.src = "images/nav_new_roll.jpg";
com = new Image();
com.src = "images/nav_comm.jpg";
com_m = new Image();
com_m.src = "images/nav_comm_roll.jpg";
cont = new Image();
cont.src = "images/nav_cont.jpg";
cont_m = new Image();
cont_m.src = "images/nav_cont_roll.jpg";

resp = new Image();
resp.src = "images/chk_wrk.jpg";
resp_m = new Image();
resp_m.src = "images/chk_wrk_roll.jpg";

floor_w = new Image();
floor_w.src = "images/floor-work.jpg";
floor_wl = new Image();
floor_wl.src = "images/floor-work-roll.jpg";

foot = new Image();
foot.src = "images/alt_foot_home.jpg";
foot_m = new Image();
foot_m.src = "images/alt_foot_home_roll.jpg";
foot_d = new Image();
foot_d.src = "images/deck-footer_home.jpg";
foot_dl = new Image();
foot_dl.src = "images/deck-footer_link.jpg";
foot_f = new Image();
foot_f.src = "images/floor-home.jpg";
foot_fl = new Image();
foot_fl.src = "images/floor-home-roll.jpg";

<!-- repeat the 4 lines above for any subsequent images. -->

function swap(){
if (document.images){
for (var x=0;
x<swap.arguments.length;
x+=2) {
document[swap.arguments[x]].src = eval(swap.arguments[x+1] + ".src");
}
}
}