Start using CSS style.
The important in this example is
<style type="text/css">
body {text-align:center;}
table {margin:0px auto;}
</style>
where '0px auto' means that upper and lower margin are 0px
and that left and right margins will be AUTO adjusted to put table in CENTER
When I start code with CSS, I always use some border:1px solid somecolor;
This way I can see how big each div or element is
and how they are located at screen.
Then I adjust to move them.
Finally I remove the border colors when things look right in browsers.
td.xxx img.yyy {width:1000px; height:655px; border:1px solid red;}
This means IMG tag class="yyy"
inside TD tag class="xxx"
should have w=1000 h=665 and one border 1px red
Here is my complete HTML. IT looks alright in IE-7
<html>
<head>
<style type="text/css">
body {text-align:center;}
table.tb1 {margin:0px auto; border:1px solid blue;}
table.tb1 td.xxx {border:1px solid green;}
td.xxx img.yyy {width:1000px; height:655px; border:1px solid red;}
</style>
</head>
<body>
<table class="tb1" cellpadding="0" cellspacing="0">
<tr>
<td> </td>
<td class="xxx"><img class="yyy" src="myimage.jpg" /></td>
<td> </td>
</tr>
</table>
</body>
</html>