As a matter of fact, the more plug-ins your install, the successful rate is actually not proportionally increasing. :^P

I suggest you follow these steps:

1) Uninstall all whatever plug-ins that you have installed so far.

2) Download GSpot, and use it to check out the actual codec that your AVI file was encoded with. (GSpot is a freeware, just search from Google.)

3) After you know the actual codec you need, go ahead and install it.

Some other suggestions:

Player: Media Player Classic is quite a good choice.

Codec:

For MPEG-4 video (including DivX3/4/5, Xvid), ffdshow filter is quite good.

For AC3 audio, AC3 filter is quite good. You might need AC3->AVI filter as well in some cases in order to correctly decode videos with AC3 audio.