function imgSwap(oImg)
{

   var strOver  = "_hover.png"    // image to be used with mouse over
   var strOff = "_clear.gif"     // normal image

   var strImg = oImg.src
   if (strImg.indexOf(strOver) != -1) 
      oImg.src = strImg.replace(strOver,strOff)
   else
      oImg.src = strImg.replace(strOff,strOver)
}