The Richard Dawkins' BBC Television series is available for download at no charge. The 5 part series "Growing up in the universe" are made up of 5 one hour lectures by the good professor himself.

At around 100mb each the downloads won't be as high quality as the DVD versions, but they are free so who's complaining?

Links provided below for your convenience.

01 - Waking up in the universe: QuickTime | Torrent |
02 - Designed and Designoid Objects: QuickTime | Torrent |
03 - Climbing Mount Improbable: QuickTime | Torrent |
04 - The Ultraviolet Garden: QuickTime | Torrent |
05 - The Genesis of Purpose: QuickTime | Torrent |

More information can be found on the official web page.