C let's you do everything.
C++ is more convoluted but you can do everything.
Java is pretty widespread in the enterprise, especially for web programming.
.NET is the latest hot topic but has lower usage among all of them.
Since you seem to be web oriented, I would go with Java. If you just want to say your cool then .NET. If you want me to think you are cool, then C or C++.
I'm too lazy to retype everything so I will just state that .NET is NOT a language. You can use any language to run .NET stuff but .NET is not what you program with. C# is the best language for that but you can do it with C++, too. (You'll learn the difference between managed and unmanaged code but you probably want to use C#).
C# is close to C and C++ and Java so you get a lot with it.
Java is the best way to go, if not learn Visual Basic first then move to a fairly larger programming language. I took on VB with a program with only prior knowledge of HTML and CSS. VB took me to fully understand within a month. Now I really into Java, I've been working on learning Java for 2 months so far. I've learned a lot in the past 2 month, try and error, downloading and viewing tutorial like: http://www.freewarejava.com/tutorials/index.shtml http://java.sun.com/docs/books/tutorial/index.html
I've also purchased many beginner guide books on Java, Java 2: A Beginner's Guide (which is excellent), Beginning Programming with Java (good without having to have prior programming knowlegde). I have a lot of ebooks on Java (over 40). If you are interested let me know and I would be glad email you some! But back to subject here, Java is great and I am love learning it! My school offers Java courses and I am taking AP Computer Science: Java, next year! My school also offers courses on VB, which is instructed by the same teacher, who is great, and she's really amazed on how well I am into Java! Java is awesome! I love it. I really first wanted to try C or C++ but for some reason I went to Java and havent looked back yet!
bottom line, it all depends on you and what do you want to learn and if u start with a language, no matter how hard it is, Stick With It!