I found a codec pack which pretty much has what kAi posted. If you install this pack, you won't need to download anything else, the codecs in the pack will be sufficient. The pack has the following:
- AC3Filter
- CoreAAC
- CoreVorbis
- Haali media splitter
- OggDS
- VSFilter
- Customized ffdshow build
- wmv9
- Xvid's decoder

Just install this and you should be fine.
Zhentarim's Codec Pack