i just built a new htpc and i need to find some working codecs for windows media center.

ffdshow... but just download cccp
http://www.cccp-project.net/wiki/i [...] =Main_Page

FFDShow works with Vista too. Stay with the reliable, proven codecs that you've always depended on in XP.
http://www.free-codecs.com/download/FFDShow.htm

will i be able to play flac/ogg files???

K-lite works well with Vista & XP.

http://www.free-codecs.com/downloa [...] c_pack.htm

Don't get klite. Large packs like that is bad and will cause codec conflicts. Aviod all large packs.

And yes, flac/ogg are covered.