[laureon]

You might want to use the feature 'webmaster mode' in the admin control panel. When you are in 'webmaster mode' open customer/home.php in the new window by clicking the link offered. If you then click on page elements e.g. the authentication box, at the bottom of the screen you will be informed of the '.tpl' (template) files each page element is based on. All you need to do then is edit accordingly.

The main layout is found in: [skin1]/customer/home.tpl
and the head in: [skin1]/head.tpl
and the footer in: [skin1]/bottom.tpl

TIP:

If you look in [skin]/customer/home.tpl you will find in the code the tags:
{if $login eq "" }
{ include file="auth.tpl" }


{else}
{ include file="authbox.tpl" }

You can remove them from 'home.tpl' and place them somewhere in 'head.tpl'

You can then customise the templates 'auth.tpl' and 'authbox' to suit your design.

Hope this helps you out a bit.