function imageDown(imageName) 
{
    if ( eval( preCacheArray[imageName] + "_down.complete") ) 
    {
        document.images[imageName].src = eval( preCacheArray[imageName] + "_down.src" );
    }
}

function imageNormal(imageName) 
{
    if ( eval( preCacheArray[imageName] + ".complete") ) 
    {
        document.images[imageName].src = eval( preCacheArray[imageName] + ".src" );
    }
}

var preCacheArray = new Array();

function preCache(imageName, imageURI)
{
    preCacheArray[imageName] = new Image();
    preCacheArray[imageName].src = imageURI;    
}