It is very, very - VERY! -easy to screw up the playback chain when you start installing
players, codecs, splitters, etc. and manage them directly with DirectShow filter apps.
And here is the worst part: once screwed up, only reinstall can fix it (with XP)!
Don't install any codecs!
Start with a player that has nothing of its own. ZoomPlayer is (was?) a good candidate.
It gives you control over every minute detail of the playback chain. You'll get tired fiddling with it...
And if you are really missing something, install ffdshow and start enabling one by one what you need!
If memory serves, the latest ffdshow had full AC3Filter functionality by itself.
If you want visual presentation of the playback mechanism in WinXP, install GraphEdit