Hey Charlie...
No Sweat!
Actually it's easier than you might think.
It requires the use of a 'wrapper' or an outer container with a predetermined width.
For simplicity, i used your splash page as an example. Your image is 1024px wide so it made sense for the wrapper to be 1024px wide.
HTML Code:
<body>
<div id="wrapper">
<img src="Splash Screen Jpg.jpg" width="1024" height="768" />
</div>
</body>
Now of course, we have to apply some CSS to the div to make it center automatically.
HTML Code:
#wrapper {
width:1024px; //Defining the width - necessary for centering
margin:0 auto; // The magic
}
I'm sure you can apply this to your pages.
Hope it helps!
Cheers.
Mike.