wp_get_archives() output issue

First of all, what I’m trying to do is show a list of the last year (12 months) of archives. Then I want to have a link that you can click that extends the list to all of my archives (they go back to 2003).

I was trying to do this with AJAX and the XAJAX module (xajax.sourceforge.net) so the page doesn’t need to refresh to do this. Unfortunately I’m finding the wp_get_archives() function doesn’t return, it outputs. So setting it to a variable like $text = wp_get_archives(); doesn’t work. Short of actually making the SQL queries myself, is there any way to get it to return values?