AVI problems with Quicktime

Hi folks. New to Mac Forums and Macs in general. Just bought a brand new Intel iMac last night in fact. Anyway, my problem is playing AVI videos with Quicktime. Originally, I couldn't get the sound to work at all. I installed a few codecs and tried MPEG Streamclip. Streamclip originally worked and I was able to play the videos with sound, but no sound from Quicktime. However, after a reboot, both Streamclip and Quicktime play sound, but it's all sped up and distorted. Here's what Quicktime reports my format as:

Generic MPEG-4, 640 x 480, Millions
MPEG-1 Layer 2, Stereo, 44.100 kHz

I have the following components in Library/Quicktime:

AppleIntermediateCodec
AppleMPEG2Codec
DivX Decoder
DivX Encoder
Perian
XVIDDelegateMacOSX.sit
FFusion
XviD_Codec 1.0 alpha
Save as AVI


If you have any suggestions, let me know. Like I said, I'm brand new to Macs and I'm sure I messed something up here.

 

So, I tried uninstalling everything but Perian and added Flip4Mac, but no luck. I then reinstalled the Divx codecs and removed Perian and it worked again in MPEG Streamclip, but still no sound in Quicktime. I read that Perian 1.1 has caused some problems so I tried 1.0. With that, I got audio for about a second with Quicktime before it disappeared and eventually Quicktime locked up on me altogether. I guess if Streamclip is working, that's better than nothing, but I would like to use Quicktime if at all possible.

 

Yep, that's all up to date, but Perian seems to be creating more problems than helping. At the very least I can convert the files with MPEG Streamclip to a format Quicktime understands, but the file size triples (at least with MPEG-4 format). I'll have to play around with it some more to see if there's a more efficient format.