Vista Codec Pack is a neat little package that includes codecs from both big names and small that will enable you to run most videos without having to hunt for that specific player. The developers do not include a player with this package but they ensure that once you install it, you will be able to run the formats supported on you pre-installed Windows Media Player.
The official change log for version 4.6.8 is as follows:
- fix installation errors for ALL
- add full Vista UAC compliance
You may download this updated version here