Alright, so I'm not a computer geek. I try to download movies on Limewire- some are AVI, some MP4, etc. Some will play on my Window's Media, some have to be played on Quicktime. WHAT THE HELL. Can't I just download a quality movie and play it on whatever? Half the time the audio and video don't match up!! HELP ANYONE??

It's a CODEC issue. There are some players such as VLC which have built-in codecs & play most video formats. See CODECs list for Movies / Alternate players

Thanks for the helpful link.