Vista offers a built-in DVD Maker utility.
Photo Gallery is a nice photo file manager. You can add meta data to your photos.
Pidgin is an excellent freeware Instant Messenger program add-on for Vista. It offers support for AOL, MSN, Yahoo, Google, IRC, and others. Why have multiple instant messenger programs when you can have just one. During multiple conversations, each person gets their own tab.
uTorrent is an excellent P2P client. Not part of Vista, but under Vista, performance is improved over XP. During Vista's development, improvements were made to the TCP stack, resulting in faster Internet performance.