aligning adsense code in single.php

hi guys
i have added my google adsense code into my single.php so that the ads display after the title but before the post content, and also at the end of the post.

i added the code in single.php just before <div=”entry”> and also after the </div> end tag for “entry”. the ads appear fine.

i want to centralise the ads nd also add some padding around them

i have tried adding
.post_content ins {
left: 17%;
margin:5px 0;
}
to my stylesheet and this centralises the ads, but wrecks the layout in IE.

can i wrap the two google codes in a div and css instead? would this work better? i have tried finding a few things but the alignment is still wrong.