There are so many video editting programs out there. I guess AVS video editing tools, Pinnacle Studio, Adobe Premiere, etc are quite popular. With MOV files specifically, I personally find TMPGEnc 4.0 works well for .MOV to .mpg converstions. Make sure whichever you choose supports .MOV to .AVI conversions. and please know even if they say their program supports that type of conversions, you may find some glitches in outputted avi files. Some if not all of those programs give you trial periods, so I recommend that you take advantage of that to determine which one works the best for you.
I'd first transfer those video files in your camera to computer's hard drive even just for playing with Quick T but most definitely for coverting. I find that my computer has easier time playing videos that are saved on my computer than ones on an external device connected through a USB or Firewire. that sometimes makes a big difference especially for high quality video files. but where you have the video files usually affects the video playback, not so much the audio play back. I am not sure if it's a codec issue, but I think the first step is to see if playing them out of your hard drive makes a difference.
