Which codecs you have on your Vista to works well ?

I strongly urge you NOT to use any codec packs! In my experience, and that of others, they are often the cause of much trouble. We just recently had a poster who was unable to play some videos. After removing a codec pack (K-lite, to be exact) her trouble was resolved. However, it took several days and much work to resolve.

Instead, get the codecs that you need when you need them.

Here is a quick list I threw together of codecs that I have used and are stable under Vista. If you need a codec for a particular format, just ask.

BUILT-IN TO VISTA
DVD video - MPEG-2, MPEG-1, Dolby Digital audio
WMV - Windows Media Video up to WMV-HD (VC-1), Windows media audio (all), streaming

RECOMMENDED
CoreAVC (paid) - best quality H.264, MPEG-4 AVC decoding
Koepi's XviD - for MPEG 4 ASP files, DivX, XviD, and M4V
Haali Media Splitter - matroska (MKV) playback
ffdshow-tryouts - rare and oddball formats, FLV, M-JPEG, H.263, H.261, et. al.

INSTALL IF NEEDED
Quicktime - quicktime (.qt,.mov, streaming QT)
RealPlayer - Real (.rmvb, streaming rv)

firbec, there are a number of tools that everyone should have available codec "maintenance", so to speak. One of the first that you should get is MediaInfo from SourceForge:
http://mediainfo.sourceforge.net

This small, freeware tool lets you see what video and audio streams are inside any video container. Most media files, such as .avi, are containers which can hold different kinds of video and audio streams. It is the *streams* that require codecs, not the containers. Well, mostly -- there are exceptions to those statements. Use MediaInfo to look at any media file to find out what container, video stream, and audio stream are in it. Then you will know which codecs that you need to playback that file. And, again, my advice is to only install the codecs that you need.