Ffdshow codecs puzzle



my main pc has acquired a couple of ffdshow codecs somehow in the last couple of days.
when I play an avi or mpg video, I get 2 tray icons popping up - one for ffdshow video & one for audio. clicking one of the icons brings up a maze of options but no helpful documentation!

they don’t seem to be doing any harm, but they don’t seem to exist on my other PC. (a search for ffdshow finds no files anywhere on the hard drive)so I’m puzzled as to what codecs thay have replaced i.e. what codecs are being used when I watch the same video files on my other PCin WMP, or WINDVD or powerDVD ?

I’ve only knowingly installed DIvx as an actual codecs pack, & maybe AC3 filter in order to get some audio to work properly. anything else that I have would have been part of a software package installation.

I think the main PC got them yesterday when I was looking for and trying video splitting software. I googled them & they seem to have no bad side effects but I don’t seem to have full ocntrol over them. I opened the tray icos & turned then off, so now I can’t access the codec config screens as there is nothing in my start programs menu, just a couple of files in wiondows/system32 - ffdshow.ax & ffdshow manifest.

I could lose them i suppose by system restore back to a couple of days ago but that seems a bit drastic if they are not harming anything. Some sites that I googled suggest that they are better than DIVx & Xvid so maybe I should hang on to them ?
Advice please on : should I just leave them alone , or tyr to get rid of them, or should I download the “proper” and latest ffdshow codec pack if I can find the best site to get it from ? That would give me access to the codec control screens via start programs - menu, according the the documentation that I’ve read online.

and is there any easy way to find out what programs on my pc are now using those codes & what those programs were using before these arrived. ? are they only used for playback or could they now also be being used when fab rips/converts ?