Xvid and possible alike fail in Vegas ONLY (give me the right codec combination)

[Kloppstock]

Im extremely tired of not knowing what preferences Sony Vegas 9c works after, cause there will allays after a new installation be problems to add the video stream to the time line, im only getting the audio bar added on basically all normal videos i have, so its hard to point out exactly if its only xvid avi's or other avi's as well, however MPEG seems to add both video and audio for some reason

"Steam attributed could not be determined xvid"

I got so tired of seeing that no combination of codec settings can be correct from the start this time either, so i installed
K-lite codec mega pack
(and i dont need to hear that codec packs mess up your systems)
cause without it it doesn't work anyway in vegas, and that is all that cunts

So i wanna know what you who reads this and use Vegas what video codecs you have installed/vegas settings you have currently when you can add a xvid avi to your timeline

I know about Sony Vegas 10, but i dont wanna update to it and keep it, iv already tested and it causes other problems instead, so i rather be persistent and solve the Vegas 9 problem since that version have worked before!!!