It don't dare to send you the fetched file as it takes 26k (but I can!), but it is similar to the one you can see in firefox, except that the two frames are missing (the one on the left-hand side with book details, as well as the one on the right-hand side with page content and the "next page" button whose link I need). Hence, there is actually nothing between the search box and the bottom line " * © 2008 Microsoft | * Privacy | * Legal" etc.

The specific bit I need is this:
<a id="PAGENEXT" href="#t=M-BkRr2dwOhxBBOAGBtqhg&amp;page=1&amp;sq=" title="Go to next page" class="button"><img src="http://books.live.com/s/books/page_next_normal.gif" class="icon navButtonIcon"></a>

Thanks for your suggestion, but I had already set the user agent.