Codec packs are evil.
Do yourself a favor and learn how to manually install codecs. In the long run, your Windows will be thankful, resulting in a more stable system, better video playback and less reinstalls. And on top of that, you know exactly what's installed and where it's installed.
Now, for OGM files, there's normally no way around the OggDS9555 splitter, a rather crappy piece of software which has a bug that will make Explorer crash if you have the folder tasks (only applies to XP) or thumbnails enabled. Disable both of these, and you'll be fine.
On top of that, you also need the codecs that were used to encode the video and audio stream inside the OGM file.
OggDS9555 already includes an OggVorbis decoder filter.
DivX 5.1 can be found on many homepages (and eMule, of course; btw, get 5.1 and not 5.1.1 or 5.1.2 - those two versions are broken),
Koepi's XviD builds can be found via Google easily. To cope with problematic videos that trigger bugs in DivX or were created with old, broken XviD versions, also get the latest
inofficial ffdshow. You can set everything to disabled in ffdshow's codecs configuration, and only enable it for certain formats when the real decoder filter (XviD or DivX) has problems. Finally, Microsoft's
Windows Media codecs let you play videos encoded with WMV9 or older versions, even without installing Windows Media Player 9.
As for audio: Besides OggVorbis, you'll probably need the
AC3Filter (available from SourceForge) to play many DVD rips, and
CoreAAC. The latter is quite rarely used still, but it can be found in use in a few recent high quality encodes.
To make the list complete, the
Matroska splitter provides support for mkv videos, and
VSFilter plays embedded or external video files, with full support for SSA v4+ style effects and formatting, as well as many other subtitle formats.
With these filters and
Zoom Player, you should be able to play almost all videos without problems. The exceptions to this are OGM videos that trigger the aforementioned bug in OggDS9555 which makes ZoomPlayer just give up and close, without a warning usually. In this case, it's good a idea to have one of these two alternative players: Gabest's
Media Player Classic has a built-in OGM-splitter that works, and the
Video Lan Client has everything built in and is completely independent from any external filters or codecs.
The only major formats that are missing so far are QuickTime (but who needs that anyway?) and Real Media (but who... you get the idea). For both of these formats, some people have written decoder filters that allow QuickTime and RealMedia files to be viewed in other, DirectShow aware players (such as ZoomPlayer), without installing the usually spyware ridden commercial players. Both filters can be found via Google easily.
That's all you really need. Don't let someone push a codec pack on you because it has one filter that is claimed to magically solve your problem. There is no such thing as magic. If you lack a filter, get that one filter and install it, not an entire pack. Would you buy 20 hens to make one omlet?
Finally, about fixing your current playback problems...
First, deinstall any and all codec packs. If you can still play an ordinary DivX 3 AVI file with MP3 sound after that, praise yourself lucky. Otherwhise the codec packs have crippled your DirectShow filters and you're in for a trip to the Windows Setup CD. Assuming that you're not reinstalling, fetch a tool such as GraphEdit or ZoomPlayer Pro's integrated filter management (word of warning: I haven't tested that yet and have actually no idea how well it works) and look for filters that are registered but don't belong into your DirectShow configuration. The huge problem is identifying those filters and telling them apart from ones that are part of a default Windows installation, and to be frank, even I can't do that (without looking at a newly installed Windows as reference). Once found, deregister the rougue filters, install the codecs and filters listed above and hold your breath while trying to play an OGM video in ZoomPlayer.
