With these packages installed you won't need to install any other codecs.
When dealing with codecs, more does not equal better.
Having the least amount on your system is the best configuration.
This is exactly what the Vista Codec Package does for you.
You will no longer be restricted to using a specific player on 32bit or 64bit.
Vista MediaPlayer and MediaCenter will be able to play all your files.
Updated: 18th-August-2008
Vista 32bit MediaPlayer & MediaCenter Codecs: (everyone needs this version) |MG| Vista Codec Package 4.7.3 Final Vista 64bit MediaPlayer & MediaCenter Codecs: (64bit users only, after installing the above) |MG| Vista Codec x64 Components 1.5.2 Final 64bit NOTE: Vista Ultimate 64bit uses the 32bit player as the system default. The X64 Components include icons to allow you to change the system's default player between the 32bit and 64bit Windows Media Player(s).
One other aspect of Vista x64 Windows Media Player(s) needs to be mentioned. If you associate a particular filetype to open with WMP while the system default is set to use the 64bit player, that filetype will always open the 64bit player when doubleclicked. This occurs even if you change the system default back to using the 32bit player.
Vista Codec Pack Tools & Extras
The Vista Codec Package no longer includes any QuickTime components. VCP is fully capable of MOV and 3GP playback without any QuickTime software installed. This release of QuickTime Lite for VCP uses the original MSI installer from Apple to install a 'lite' version of QuickTime which will provide full browser support for viewing and downloading QuickTime files.
Media Player Classic addon 
XvidVideo.RU Media Player Classic is an extremely light-weight media player for Windows. It looks just like the good-old Media Player v6.4, but has lots of nice extra features.
MPC has, for instance, a built in DVD player with real-time zoom, support for AVI subtitles, QuickTime and RealVideo support and lots more. (keys 2,4,6,8 for Video Zoom)
Definitely a great replacement for the huge and clumsy Microsoft Media Players.
GSpot is a codec identification utility - identifies which video and audio codec compression method is used on any file, whether the matching codec is installed, and more.