VLC (formerly VideoLan Client) is a windows based media player that can play almost any multimedia file type. Version 0.8.5 recorded 29 million downloads and here is the new version with many new bugfixes and features. This player is light on system resources and does not feature a bloated and 'ultimate RAM eater' interface such as in Windows Media Player. But it definitely delivers more features and more compatibility with file types than Windows Media Player (and than most other players that are in existence today).
Change log from 0.8.5 to 0.8.6:
* Support for Windows Media Video 9 and VC-1
* Support for VP5/VP6 and Flash video
* Support for TTA and WavPack Lossless audio
* Much improved H.264 support
* Preliminary DVR-ms, MXF support
* Shoutcast TV support
* Windows unicode fixes
* Apple Remote supp
How to get it:
Get VLC Media Player 0.8.6: Download Now! (Direct Download)
No crack is required since it's open source.