Many people dislike RealPlayer, a software with a bad reputation and an intricated interface. While there are many tricks to play Real media files without using RealPlayer, Scott, a read of this blog, found an interesting version of RealPlayer that does its job without displaying ads and without unneeded features: RealPlayer for Enterprise.
"RealPlayer Enterprise gives you the best of RealPlayer you know and use at home, but without advertising, without requiring registration, and without consumer features that don't belong in the workplace."
The software actually does one thing: it plays files. You'll be surprised by the spartan interface and by the small numbers of options in the menu.
You can read more about RealPlayer for Enterprise here. To download the setup, you need to complete a registration form (the email doesn't need to be valid).
This is a version from 2004, so don't expect a slick interface.