lol, wannabe bill gates?
I'd recommend VLC player:
http://www.videolan.org/vlc/
It can play most files and since you want to watch anime, I can assure you it'll come in handy very often.
As for the codec, I'm not sure what you've downloaded, but I'd recommend the Combined Community Codec Pack:
http://www.cccp-project.net/
And if you have trouble installing the latter, you can simply read the FAQ on that site or check their forum.
Let us know if you have any more questions/problems.
You might want to check this thread:
Anime Playback Guide With Pictures ^^