did you try "real alternative"?
my computer runs just about everything with minimal codecs. (I dont want to seem like im bragging, i'm just sharing my experience that have worked for myself. Its a stable system with minimal conflicts)
i use media player classic. I have a xvid codec to run all divx coedecs, I have a ogg codec, I use real alternative, quicktime alternative, wmv lite, and ffd show. I also installed all the newer windows media player codecs for 6.4 from Microsoft website. My computer doesn't have any windows media player installed except for 6.4 (using nlite), My video card has a bug where it wont play quicktimes within an internet browser so I use "media player connectivity" for fire fox.
All my videos run in mpc now. even the ones within firefox.
Thats really all you need. I have had experiences with codec packs breaking windows. sometimes they uninstall necessary files. other times they add codecs and conflict with ones already installed. Its might work with a fresh install of windows, but codec packs are risky on a computer with codecs already installed on it. It can cause crackling and poping. Frustrating if its for first time getting that kind of thing. it can take forever to find the problem. especially when you dont know that conflicting codecs can do that kind of thing.