Try using hover, the benefit being that you can specify the mousein and mouseout events in the same function. If you need any help with specifically how to apply what you've got to the hover event, just comment and I'll see what I can do.
EDIT:
Ok, the code on your site already has this
//On mouse over those thumbnail
$('.zitem').hover(function() {
//Set the width and height according to the zoom percentage
width = $('.zitem').width() * zoom;
height = $('.zitem').height() * zoom;
//Move and zoom the image
$(this).find('a img').stop(false,true).animate({'width':width, 'height':height, 'top':move, 'left':move}, {duration:200});
//Display the caption
$(this).find('div.caption').stop(false,true).fadeIn(200);
},
function() {
//Reset the image
$(this).find('a img').stop(false,true).animate({'width':$('.zitem').width(), 'height':$('.zitem').height(), 'top':'0', 'left':'0'}, {duration:100});
//Hide the caption
$(this).find('div.caption').stop(false,true).fadeOut(200);
});
I'm going to add two lines into this code that do what you want
//On mouse over those thumbnail
$('.zitem').hover(function() {
//Set the width and height according to the zoom percentage
width = $('.zitem').width() * zoom;
height = $('.zitem').height() * zoom;
//Move and zoom the image
$(this).find('a img').stop(false,true).animate({'width':width, 'height':height, 'top':move, 'left':move}, {duration:200});
//Change the header colour
$(this).siblings('h2').animate({'color':'#111111'},250,'linear');
//Display the caption
$(this).find('div.caption').stop(false,true).fadeIn(200);
},
function() {
//Reset the image
$(this).find('a img').stop(false,true).animate({'width':$('.zitem').width(), 'height':$('.zitem').height(), 'top':'0', 'left':'0'}, {duration:100});
//Change the header colour back
$(this).siblings('h2').animate({'color':'#EE4E07'},250,'linear');
//Hide the caption
$(this).find('div.caption').stop(false,true).fadeOut(200);
});
That should do it