FFDShow not being used at all.

Ok, so I recently re-installed windows (XP) and wanted to re-install FFDShow, so I did, and I ran a couple audio/video files and the FFDShow tray icons weren't showing up, so I edited a few things that would be easily noticed in the settings (such as OSD) and none of them showed up, so I think that FFDShow isn't being used, at all. I have no idea how to get it to work, I've tryed: ffdshow_beta6_rev2527_20081219.exe and ffdshow_rev3119_20091027_clsid.exe neither of which, worked. Any help?

Media Player Classic

Though it doesn't work for Sony Vegas either

I tried the merit on preffered, default, and very high, nothing happend. In GraphStudio, the ffdshow(audio) came up and worked just fine. but when loading a video it said it could not render video(.mp4), I'm going to go get a different video type to test it with.

Edit:
The video works just fine too, in GraphStudio(mpeg). works like its suppost to, but anyhing else, does not.

Edit Edit:
I got the audio and video to work on .mpeg files, and the audio to work on .mp3. But it wont work on .mp4 video files, and i don't know why

Thanks for the replies, I got the mp4 working fine, just had to change a few things in ffdshow. But in Sony Vegas, when playing an mp4 it goes extremely slow and is more like a slideshow of a couple parts of the video, but when rendered and saved to an mp4 it works just fine (or any other format)