var dThisDoc = document;

function preloadImages()
{
    if (dThisDoc.images)
    {
        var nIndex;
        var nNewPictureIndex;
        var saArguments = preloadImages.arguments;
            
        if(!dThisDoc.iaPictures)
        {
            dThisDoc.iaPictures = new Array();
        }

        nNewPictureIndex = dThisDoc.iaPictures.length;
        
        for (nIndex = 0; nIndex < saArguments.length; nIndex++)
        {
            dThisDoc.iaPictures[nNewPictureIndex]       = new Image;
            dThisDoc.iaPictures[nNewPictureIndex].src   = saArguments[nIndex];
            nNewPictureIndex++;
        }
    }
}

function turnImageOn(psImageName)
{
    document.images[psImageName].src = "images/" + psImageName + "-on.gif";
}

function turnImageOff(psImageName)
{
    document.images[psImageName].src = "images/" + psImageName + ".gif";
}