imgNms = new Array('events',
                   'clients',
                   'team',
                   'contact');

ovrImg = new Array('images/navicon_l_o.gif',
                   'images/navicon_l_o.gif',
                   'images/navicon_r_o.gif',
                   'images/navicon_r_o.gif');

outImg = new Array('images/navicon_l.gif',
                   'images/navicon_l.gif',
                   'images/navicon_r.gif',
                   'images/navicon_r.gif');

imgCnt = imgNms.length;
ovrPic = new Array(imgCnt);
outPic = new Array(imgCnt);

for (var i=0 ; i<imgCnt ; i++)
{
  ovrPic[i] = new Image;
  ovrPic[i].src = ovrImg[i];
  outPic[i] = new Image;
  outPic[i].src = outImg[i];
}

function swImg(imgNum, imgState)
{
  if (document.images)
  {
    var imgName = imgNms[imgNum];
  
    if (imgState == 1)
    {
      document[imgName].src = ovrPic[imgNum].src;
    }
    else if (imgState == 0)
    {
      document[imgName].src = outPic[imgNum].src;
    }
  }
}