Get CCCP which is also known as Common Community Codec Pack.

Consist of :
- AC3Filter (Decoding the obvious)
- CoreAAC (Decoding aac audio)
- CoreVorbis (Decoding *drumroll* vorbis audio)
- Haali media splitter (Best splitter out there. It's also updated more often then Gabest's, and author listen to appropriate suggestions)
- OggDS (For your ogm relics)
- VSFilter (For any softsubs)
- Customized ffdshow build (For general mpeg4 playback like lavc/h264)
- Xvid's decoder (For decoding the obvious)

FAQ

Even allows you to play the latest H.264 codec files.


(Taken off from Zhentarim DivX and KickAssAnime webpage)