Hey, not sure if i'll be able to help but i just started learning about this subject. I've used limewire pro to download my movies ( I'm on dial up so it takes a long time ) but what I've found was this... I only download movies that has been dvdripped from "xvid." If you tend to use this, you will need the xvid codec, goto google.com and look for it... Most of the xvids i've seen is in .avi format, its great quality. Most of these files are 700 megs or higher.

Also you may want to go download the divx codec/ player, if you download some of the "divx" dvd ripped movies, but either way the divx player seems to run eithen the xvid movies better than windows media player from my experience.

heres the link for that... hope this helps
http://www.divx.com/divx/download/