Struggling to get integrated

First off, I'm new to G2 so if I 'm missing any basics let me know.Or if there is a man page I might have missed please do point it out ;)

I am trying to create a site with a simple menu bar at the top of the page that links to several pages, one of those links is to g2.

My index.php in my site root:
<?
$task = $_GET['task'];
if($task == 'gal2'){ //want to view gallery
include_once('gallery2/gallery2embedded.php');
} else { //load one of static pages
include_once 'topmenu.php';
switch($task){
case 'other':
include_once('other.php');
break;
default:
echo 'Welcome';
}
include_once 'footer.php';
}
?>
Nothing exciting there.
topmenu.php is a table with links back to the index page above (with appropriate get params).
footer.php just contains text for testing.

Now then, at the url www.frozenbanana.co.uk/ you will see the index page. Click the gallery link to start the gallery - so far so good.
But when I click on login it just redirects to index.php with default content.

I have tried resetting the .htaccess/mod_rewrite.
Tried clearing cookies and even using differant browser(s).
To no avail.

I can get the login form fine if I go direct to www.frozenbanana.co.uk/gallery2/

In my /gallery2/gallery2embedded.php I have the following:
$g2_Config['embedPath'] = '/';
$g2_Config['g2Uri'] = '/gallery2/';
$g2_Config['loginRedirect'] = '/';
//$g2_Config['embedUri'] = '/gallery2/gallery2embedded.php';
$g2_Config['embedUri'] = 'index.php?task=gal2';

I have found docs that tell me what to change these to, but simingly no explanation as to what they are/what they do.
eg. is embedUri the uri for the page that will include the gallery2embedded.php or the uri to the gallery2embedded.php?

given that the site index page lives at:
/index.php
gallery installed at:
/gallery2/
the embed script:
/gallery2/gallery2embedded.php

I suspect it is something in the .htaccess or these mysterious variables, but if someone can help me pin it down a bit more it would be much appreciated!

Long post, thankyou if you made it to the bottom!

I've updated the wiki to hopefully help those that are having issues with understanding what the paths are supposed to be.

http://codex.gallery2.org/Gallery2:How_to_visually_embed_G2_in_your_own_website_using_embedded_mode

Steve Lineberry