Okay well I seem to be working in the right direction with this, but would still greatly appreciate any nudges!
I have shrunk the resolution of the main image, and that has brought the right column in, however there is still an uneven amount of white space between the centre column and right column that I'd love to minimise. You can see what I mean here:

And I've tried to centre align the content of the two sideboxes in the right column by adding a class to stylesheet.css:
Code:
.centeredImage
{
text-align:center;
margin-top:0px;
margin-bottom:0px;
padding:0px;
}
Then calling it in each definition of the sideboxes:
Code:
define('TEXT_FANBOX_SIDEBOX', '<p class="centeredImage"><fb:like-box profile_id="116954695015876" width="140" connections="4" stream="false"></fb:like-box></p>');
Code:
define('TEXT_BLANK_SIDEBOX', '<p class="centeredImage"><img src="/includes/templates/pure_red_free/images/payments.gif" alt="Payment Options"/></p>');
But I still have excessive whitespace above/below the content in each sidebox.
Any help at all would be amazing!