Once you've got certain basic concepts of computer science down, switching to a new langauge is just a matter of getting used to a new syntax ( though quite a few languages use a C style syntax anyway ), and new library interfaces. I think its far more important to master these concepts before "deciding" on any specific language to learn. After all, what's the point of trying to guess which language you'll need for a job? We could sit here all day making guesses, and still be wrong.
Do you have any programming or CS experience yet? If not, I suggest you start off with Python (
www.python.org ). It's a simple, portable, and newcomer-friendly language. They've got several tutorials right on their website that not only assume the reader is new to Python, but to programming in general. That's the best place to start, IMO. You'll be able to get the basics down without being overwhelmed with implementation details.
Java is also a decent beginners language, because it also hides a good amount of the low level stuff, and it has excellent documentation. However, its easy to learn bad habits in Java: relying heavily on the garbage collector will lead you to create programs full of memory leaks in other, lower level langauges, for example.
Once you've mastered the basics, C is a good choice to learn. The language itself and the supporting C standard library is small, unlike C++, for example. This makes it easier to learn and to program with, IMO. C will force you to deal with the lower level issues, like memory allocation, buffer management, etc, by yourself, which I think is a good thing and will make you a stronger programmer.
After you've got yourself a strong foundation, learning new languages will not be difficult. If you don't have this foundation, however, you'll have trouble with relatively trivial things in your "chosen" language, and will be totally clueless should you ever need to switch to a different language or platform.
