I'm proudly presenting Oggcodecs "Nikolaus" release.
This version has lots of bugfixes, particularly to Theora and FLAC. I've added support for Windows x64 versions.
For Windows XP x64 you will need to use Media Player Classic Home Cinema or some other 64 bit player, because Windows Media Player doesn't install the 64 bit version.
If you want to use Windows Media Center on Windows Vista x64 you will need to point it to the 64 bit Windows Media Player.
Windows Vista x64 has the 32 bit version of Windows Media Player set by default. For more information about this issue visit this page.
Oggcodecs installer sets the file associations to the 64 bit version of Windows Media Player, so it will work out of the box without needing to switch on the 64 bit version.
For more information about the release visit the Oggcodecs DirectShow homepage