I use Episode Pro and use 25Mbps 2 pass CBR to ensure my entire encode is at their peak acceptable data rate.
So far I’ve found the best way to confirm the quality of the encode is with VLC.
I’ve found that MPEGStreamclip and Quicktime don’t seem to playback the program streams well.
You don’t mention your source AVI but I’ve even got good results with DVCAM MOV source (I’m on Mac so I’m using MOV).
AVI is a wrapper so what’s in there can make a big difference.