Uninstall Real Player and Quicktime, then get the Real and Quicktime Alternatives on the free-codecs site. With these installed, you can play the movies in a general player, such as Media Player Classic. I think VLC is capable of using the codecs as well, but I am not sure since it tends to go against propriety and integrates its own codecs...
Personally, I think MPC is a better player than VLC. Try them both and see which you prefer. Both can even play DVDs, so you don't need any shoddy DVD programs (such as Cyberlink PowerDVD) either.
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