Popup Images

Does anyone have any advice on what I should use to set up some images I have thumbnails of so that if the user scrolls over the image, it pops up and if they click the popped up image which should be now bigger and in detail in a new window using Flash or something else so that when I'm finished and have clicked on the bigger image, it should disappear rather than closing said newly opened window.

My friend has said he's seen ads like what I'm describing on Yahoo News, but I can't find a proper example.

Thanks in advance!