My favourite Mediaplayer is K-Lite Mega Codec Pack with Mediaplayer Classic. The reason is that the codec pack is MEGA, it has support for almost everything you'll need to play. A "small" list from their website shows the codecs:
DirectShow video filters:
- XviD [version 1.2.0-dev build 2006-11-02]- DivX [version 6.5.1.0]
- On2 VP6 [version 6.4.2.0]
- On2 VP7 [version 7.0.10.0]
- MPEG-1 / MPEG-2 (Cyberlink) [version 6.0.0.3402]
- MPEG-1 / MPEG-2 (InterVideo) [version 7.0.27.191]
- MPEG-1 / MPEG-2 (DScaler5) [version 0.0.8.0]
- MPEG-1 / MPEG-2 (Gabest) [version 1.0.0.3]
- MPEG-1 / MPEG-2 (MainConcept) [version 1.0.0.78]
- MPEG-1 / MPEG-2 (Ligos) [version 4.0.0.77]
VFW video codecs:
- XviD [version 1.2.0-dev build 2006-11-08]
- x264 [rev. 600]
- Windows Media 9 VCM [version 9.0.1.369]
- On2 VP6 [version 6.4.2.0] [Encoding]
- On2 VP7 [version 7.0.10.0] [Encoding]
- Intel Indeo [version 5.2562.15.54]
- Intel Indeo [version 4.51.16.2]
- Intel Indeo [version 3.24.15.03]
- Intel I.263 [version 2.55.1.16]
- huffyuv [version 2.1.1 CCE Patch 0.2.5]
- I420 (Helix) [version 1.2]
- YV12 (Helix) [version 1.2]
QuickTime Alternative:
- QuickTime codecs [version 7.1.3.100]
- QuickTime plugin for Internet Explorer
- QuickTime plugin for Firefox/Mozilla/Netscape/Opera
- Extra QuickTime plugins
- QuickTime DirectShow parser
- QuickTime DirectShow decoder wrapper
Real Alternative:
- RealMedia codecs [version 6.0.12.1741]
- RealMedia plugin for Internet Explorer
- RealMedia plugin for Firefox/Mozilla/Netscape/Opera
- RealMedia DirectShow splitter [version 1.0.1.1]
DirectShow audio filters:
- MP3 (Fraunhofer) [version 1.9.0.311]
- AC3/DTS/LPCM (AC3Filter) [version 1.11]
- AC3/DTS/LPCM (InterVideo) [version 7.0.27.191]
- MP1/MP2 (MainConcept) [version 1.0.0.78]
- Vorbis (CoreVorbis) [version 1.1.0.79]
- AAC (CoreAAC) [version 1.2.0.575]
- AAC (3ivX Pro) [version D4 4.5.1]
- MusePack [version 1.0.0.3]
- Monkey's Audio [version 1.00]
- WavPack (CoreWavPack) [version 1.0.3]
- FLAC (illiminable) [version 0.73.1936]
- Voxware MetaSound [version 1.0.0.12]
- AAC encoder (3ivX Pro) [version D4 4.5.1]
ACM audio codecs:
- MP3 (Fraunhofer) [version 3.3.2]
- MP3 (LAME) [version 3.97]
- AC3 (ffcHandler) [version 1.3.1]
- Vorbis [version 0.0.3.6]
- DivX

Audio [version 4.2.0.0]
DirectShow source filters:
- MP4 splitter (Haali Media Splitter) [version 1.6.400.11]
- MP4 splitter (Gabest) [version 1.0.0.3]
- Matroska splitter (Haali Media Splitter) [version 1.6.400.11]
- Matroska splitter (Gabest) [version 1.0.2.9]
- Ogg splitter (Haali Media Splitter) [version 1.6.400.11]
- FLV splitter (Gabest) [version 1.0.0.1]
- MPEG-TS splitter (Haali Media Splitter) [version 1.6.400.11]
- MPEG demuxer (Cyberlink) [version 1.0.0.4528]
- MPEG demuxer (Gabest) [version 1.0.0.3]
- MPEG demuxer (MainConcept) [version 1.0.1.20]
- MPEG demuxer (Elecard) [version 1.0.31.51211]
- MP3 Source (DCoder) [version 1.3]
- SHOUTcast Source [version 1.0.0.1]
DirectShow subtitle filter:
- DirectVobSub (a.k.a. VSFilter) [version 2.37]
- DirectVobSub (a.k.a. VSFilter) [version 2.33]
DirectShow audio filters (general purpose):
- Morgan Multimedia Stream Switcher [version 0.9.9]
It is my favourite because it is:
- It replace windows mediaplayer, real player & quicktime
- Simple
- Without all the fancy stash
- It gives you what you want, and uses minimal CPU
- You can controll so many features and EQ's with the program
- It is small, easy to use, and it works
If you too want to take a look at this mediaplayer, and download it for free, visit
www.k-litecodecpack.com (btw. sorry for the long list of codecs, but K-lite delivers

)