[jQuery] Vertical center img in a div trouble

[jQuery] Vertical center img in a div trouble


Hi folks
Please forgive me if this is discussed elsewhere, but I haven't found
anything that helps. Also, please forgive the clumsy code - I'm just
starting to really figure out how to use js and jquery properly. I
plan to chain these together, but I want to get it working first!
I'm trying to center an image in a div, but it's only working some of
the time. My code:
function swapPhotos(newImg) {
    if (activePhoto == 0) {
        activePhoto = 1;
        $("#photo2").html(newImg);
        var oV = 197 - $("#photo2 img").height() / 2 + "px";
        $("#photo2 img").css({ 'top': oV }).fadeIn("slow");
        $("#photo1 img").fadeOut("slow");
    } else {
        activePhoto = 0;
        $("#photo1").html(newImg);
        var oV = 197 - $("#photo1 img").height() / 2 + "px";
        $("#photo1 img").css({ 'top': oV }).fadeIn("slow");
        $("#photo2 img").fadeOut("slow");
    }
    $(".caption").text($(newImg).attr("alt"));
}
newImg is a piece of html with an img tag in it, returned from $get.
The swap happens every few seconds, but jQuery sometimes returns the
correct image height, sometimes not.
Here it is in action:
http://dev.vigoratecommerce.com/iSynApp/userGroupDisplay.action?sid=71&urgId=10000
Any help would be greatly appreciated.
cheers
dafydd