function imgSwap(oImg)
{
var strOver  = "-on"    // image to be used with mouse over
var strOff = "-off"     // normal image
var strImg = oImg.src
if (strImg.indexOf(strOver) != -1)
oImg.src = strImg.replace(strOver,strOff)
else
oImg.src = strImg.replace(strOff,strOver)
}