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<< I'd be spending more time with Java or C# than C. >>
Anything you can do with Java or C# can be done with C. >>
I think AMDpwred was hinting that C# and Java are more contemporary than C, meaning a more marketable/"important" language to know. If that's the case, I'll partly agree with Java and a little more so with C#. Personally, I'd recommend looking into C++ simply because it's (essentially) a superset of C. Most of C is contained in C++, and you get the nifty OO features. My two cents.