I know that the majority of problems with viewing these various files stem from missing codecs. I don't know why the Quicktime on my laptop here (just the plain jane 7.x while I have the 6.x Pro on my desktop) plays the Quicktime (.mov) files just fine and my Media Player plays the Mpeg files just fine. It might be because of some other program installed on my computer that already had the codecs installed.
However, I did a little bit of research and I found alternative programs for both Quicktime and Real player and a Codec package as well. If you're willing to try them out, I found them all at
www.free-codecs.com
Look for:
Quicktime Alternative
Real Alternative
K-Light Codec Pack (comes in several flavors - I'd recommend the Full to get them all)
The codec pack would be the minimum you'd need if you already have the other players installed.
