Dragable Image Being Used As Link

I have some images that I want the user to be able to move around the page. So far, this script in the header allows me to do this:
var ie=document.all;
var nn6=document.getElementById&&!document.all;
var isdrag=false;
var x,y;
var dobj;
function movemouse(e){
if (isdrag){
dobj.style.left = nn6 ? tx + e.clientX - x : tx + event.clientX - x;
dobj.style.top = nn6 ? ty + e.clientY - y : ty + event.clientY - y;
return false;
} }

function selectmouse(e) {
var fobj = nn6 ? e.target : event.srcElement;
var topelement = nn6 ? "HTML" : "BODY";
while (fobj.tagName != topelement && fobj.className != "dragme"){
fobj = nn6 ? fobj.parentNode : fobj.parentElement;
}

if (fobj.className=="dragme"){
isdrag = true;
dobj = fobj;
tx = parseInt(dobj.style.left+0);
ty = parseInt(dobj.style.top+0);
x = nn6 ? e.clientX : event.clientX;
y = nn6 ? e.clientY : event.clientY;
document.onmousemove=movemouse;
return false;
}}

document.onmousedown=selectmouse;
document.onmouseup=new Function("isdrag=false");
The body has this:
<img src="images/balloons.gif" class="dragme">

Now, to be able to use this image as a link, I would have to find the displacement between the mousedown and mouseup coordinates. If the displacement is below say 10px, then the mouseup would bring them to another page. I also wanted to make it so that if the mouseup occurs in a certain area of the page, that the image would move itself to a certain spot.