what script shoul i use for a ajax modal window ... but i want to appear only first time when a visitator enter the site ...
well, jquery have many plugins for modal window (also called Lightbox) so for Jquery check out this: http://line25.com/articles/rounding-up-the-top-10-jquery-lightbox-scripts and also you could check this out: http://webdeveloper.econsultant.com/css-lightbox-variations