Well, Lightbox is OK, but it's just as easy to customize it yourself and write your own code for it. In fact, I did that for a little gallery on my hard drive because I didn't like the way LB handled the CSS and layer(s).
I myself found it more reliable to use a div with position: static at 100% x 100% and then use the display: table & display: table-cell on two nested divs to enable both vertical and horizontal centering so I don't have to fool with that negative margin nonsense.
Also using jQuery, I made it so that the images automatically rescale based on the window size (IE window size - margin = max-width/height). So if you go full screen, then image adjusts. It's pretty sweet and really simple.
Jquery is a pretty damn sweet library.