well, what you need to remember is that the CW3000HD is, more or less, a Computer. So really, its a matter of what OS/programs are on your computer
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Check with Netflix Support to see if their player is Linux compatible.
One thing you can do with the Hard Drive (once installed of course) is install.
you could, in theory mind you, install a WindowX OS (such as Kubuntu 8.04), which you could still install the update files WITHIN, thus making a complete tv/desktop/internet experience in your living room. If your willing to get down and dirty, you could integrate the update files to Kubuntu, then also install Wine in Kubuntu, allowing you to use .dll's & .exe's, which would run other programs, such as WinAmp, WMP, Nero, utorrent and MANY Windows Games (Halo, SIMS, etc)
there's really all kinds of things you could do with a CW3000HD, providing you know what your doing, and how to do it.