need Help with mov files..

[Slain]

ok, ive recently downloaded a couple of movies in .mov format. I have quicktime 6 pro and i cant get any video it keeps saying "you may experience problems playing a video track in "name of movie file" because the required compressor could not be found. would you like to close the movie or continue?" so i hit continue and i just get a white screen but the sound still plays. i tryed converting the video with the Rad video tools and i still just get a white screen! Please help.
Thanks in advance
Slain

[setarip]

It probably requires the 3IVX codec...