Christian Romney

Learn three or four languages. For truly heavy computations and for serious scientific programming you really ought to learn C. It's also the de-facto gold standard of the computer industry. Chances are whatever computer you're on is running hundreds of thousands of lines of C code at this very instant. There's no shortage of freely-available learning material out there, and it's a skill you will never regret having acquired.

Unfortunately, your question is a little bit like: "which tool should I learn to use-a hammer or a drill?" The answer, of course, is both. I'd recommend you start with C and then broaden your field of view with something like this: http://pragprog.com/...-in-seven-weeks

Disclaimer: I'm a software development consultant by trade, specializing in systems integration and commercial websites and applications. I've been paid to write code in C, C++, C#, Visual Basic, Java, Ruby, PHP, Perl, Python, and Javascript.

Well, that said, I can't help but link to what I think are the greatest source of video lectures on computer programming:

 

The Sussman/Abelson SICP lectures

 

While this course is intended for freshmen, I wouldn't recommend it for beginners. If you are a well seasoned imperative programmer who's wondering what all this functional stuff is about, these are a great series of lectures I would love for you to watch.

I second this recommendation, but I think the admonishment against beginners depends on the type of beginner. It's not easy material, but it's worth the effort. Also recommended is the accompanying textbook, which is worth every penny.