Here's a preview
http://www.youtube.com/watch?v=HvOXjfrda2g
First off download this
http://cccp-project.net/
and use windows media player classic to view the vids.
You can go to these sites and search for Gurren-lagann
http://www.datorrents.com/
http://www.tokyotosho.com/
or get the first 19 episodes from here
http://order.kipsta.net/releases.php