Adding avatar next to top "login here"

Hi all,

I want to mimic Facebook and add the avatar for logged-in users to appear to the right of their name in "Welcome back, USER!" at the top of Blogs MU. Including the avatar would also resemble the sidebar login widget. I suspect it has to do with these lines in header.php but I'm not sure what to add.

<?php } else { ?>
<?php _e("Already a member?",TEMPLATE_DOMAIN); ?> <a href="<?php echo get_settings('home'); ?>/<?php echo get_members_login_slug(); ?>/"><?php _e("Login here",TEMPLATE_DOMAIN); ?></a>
<?php } ?>

Thanks for any help or suggestions! Love this theme.