All the above are correct. What I want to add as a web developer myself, is that each server side technology you need to use and you could select, have something special to offer not in the sense of software constructs - because all are highly competitive and offer virtually everything, but in the sense of usability, easiness in certain aspects, maintenance etc. That said, I mean that using for instance .NET technologies, it is granted that you will have two primary advantages: easiness in coding and much ready-to-use software by many developers worldwide.There is no doubt that we are talking about leading edge technologies, but as you probably know already, though much free software has been released lately, using Microsoft technologies, in the Enterprise level, is always connected with high costs and to be honest, I think they're right.They offer solutions and help in any kind of software problem, so this must be paid.
The other side of coin. open source software, offers very good technologies and solutions for the web( PHP, Java technologies, Perl,...), many frameworks to work in and have ready-to-use code for free and in some cases even at the Enterprise level(!),or with some small fees. Their support has got dramatically better recently(talking about the last 3 - 4 years or something like that).
So it's up to you, what branch you will eventually follow and your decision must be based upon what size are the solutions you want to offer, what is your personal preference about programming(that is do you like VB programming or prefer C style,which programming language and related technologies are more attractive, convenient, etc. to you), does it serve your professional targets to choose one or the other etc.
As you see there is no "good" or "bad" programming language, technology etc. It all depends on you. For instance, it is harder to learn good C programming and even harder to learn C++, but your effort will be paid back because these are worldwide known, as the languages for "real programmers".If you wonder what C or C++ has to do with web development, I tell you that this path I followed myself without being a programmer but a web developer, and this paid back because programming in Java or PHP, or in other web programming languages became much,much easier!
Finally, the steps I would suggest for a want-to-be web developer are:
1.Very good grasping of HTML,XHTML and after these XML,if you want to work for B2B, B2C or other enterprise level solutions.
2.Very good grasping of client - side technologies and languages( I would suggest the apparent: Javascript ).
3.A general grasping and coverage of all kinds os server - side technologies, even to some low extend, so to have a general idea about all this stuff and to find which matches better to your personal preferences.
4.Mastering of a certain bunch of related technologies( e.g .NET - SQLServer, PHP - MySQL, JSP - Servlets - MySQL etc.).
There are two comments I didn't mention in this brief discussion:
First, besides the programming stuff you have to master, in the now and (hopefully) future web the role of RDBMS( Relational Database Management Systems), is of extremely high importance. So for everything beyond a bunch of static pages, with some funny easy-to-make interactions, that is not the case nowadays, the construction of a database no matter the size, is sure to be necessary.
Second, there are some factors that are not subjective in the various web technologies. For instance the use of Java as a server - side technology, is more complicated than the use of PHP for instance (at least this holds true for the most part), but the solutions Java gives you are far more professional and can be far more "Enterprise level" than the other. All you have to do is to grasp the logic of Java development, and this will lead you step by step to success.
For another instance, the use of PHP is far more better, safe and professional than older (mainly C.G.I with Perl) technologies.
As a final factor, keep in mind the day by day(hour by hour in some instances) acceptance that Open Source Software gains nowadays.
Wish you to choose the better!