i'd say go for XHTML and a little CSS next and then explore all forms of XML because in the future XML will be a pretty big part of the web.

there's no validity in saying that PHP is better than ASP.NET or vice versa unless you're referring to a very specific kind of work. ASP.NET, JSP and PHP all have their good and bad points. if you know what you want to do, then you can choose which language you would have to learn but the tool depends on your needs.

you've worked a bit with C++ and other languages right? if you have you will know what i mean then because even though C++ is probably the most powerful language out there in terms of control and stability, for some things, using C++ is just a BAD idea. it all depends on what you want to do