$(document).ready(function() {
    
    $("#thumbnails li img").live("click", function(){
        
        strSrc = $(this).attr("src");
        strOrig = $("#mainImage").attr("src");
        
        
        console.log(strSrc);
        
        strMain = strSrc.replace("/thumb-", "/main-");
        strThumb = strOrig.replace("/main-", "/thumb-");
        
        $("#mainImage").attr("src", strMain);
        $(this).attr("src", strThumb);
                                
    });
                                                          
});