What are some OOP that I can benefit from?
Depends on what you want to make. For web design PHP 5(which you already know) is a great scripting language that has many OOP features. (I actually believe they call it fully OOP now, but I might be mistaken).
For applications (which is more my area of expertise) there is a multitude of possibilities. You have to separate the company advertisement from the facts here, which isn't easy. Heres my take on the three most profiled languages: (percentages are from the last Dr. Dobb's Journal that I can recall with a survey describing the current situation(Dr.Dobb's March 2004 I believe )) C++:
Considered archaic by some and supposed to be obsolete for the last 9 years. C++ still thrives and is as a matter of fact the most used programming language (50%+ use C++ at work). It is cryptic and powerful and it's thread and pointer complexity can be frustrating at times. (Ever sat a weekend trying to find a pointer bug somewhere within several thousand lines of code? Aaargggh!)
"C++ Master Reference" (Clayton Walnum). Its an encyclopaedia where you can look up the standard functions of C++.
"C++ for MFC" is an aging and probably soon obsolete book by Richard F. Raposa. I'm not into .NET yet so I can't give you any .NET friendly advice.
(The last book is deliciously thin, much unlike those 1000 page long monstrousities that has 250 page long introductions; "I want to thank my mother, my father...(Then 249 pages later:)... and Hamtaro, the hamster I had when I was 14")Java:
Everyone expected Java to knock C++ out of the market, and for a long time it made a strong opponent. Java is user-friendly where C++ is not. Yet Sun/Java promised more than they/it could keep and these latter years the buzz has been that "Java is slow". (I do not entirely agree, but that is not something I can discuss without writing a full article on the subject). 40%+ programmers use Java at work.
I have only read Norwegian books about Java, but I have also read some excellent excerpts from Bruce Eckel's book. He is recommended by many of the sites I have visited.C# (C sharp):
Microsofts new language that is expected to knock both C++ AND java off the market. MS has the brawn to do just that, but we'll have to wait and see if they will stay focused long enough to do that, or if they launch another language within the next couple of years :p
I am not fluent with this language, so I cannot give a fair judgement. about 5% use C# at work.
Ohhh...Wait, another one:VB:
Alien* and simple. Visual Basic won't leave you much room for creativity. Yet it is fast, very fast and easy to use. Want to create applications without too much reading and hard work? Choose VB. But if you want to create complex applications like a 3D engine; stay away. (Familiar applications like Dungeon Crafter has been developed with VB)
*(for the C-family accustomed programmer (which includes php programmers))