Really any script language is usefull if you know what you are going to use it for. I mean no disrespect to vimkar, as he is entitled to his opinion, but php as with any script language really is useless if the server you are using doesn't support it. This is why I asked what you were wanting to do with it... what server support do you have... meaning what can you run? are you limited to just php? Or can you use any language and your server will handle it. If you just want to be able to alter the look of a page use xml and html. If you want to be able to do Database connectivity then you have different options. What you want to do and what choices you actually have ( support wise ) is what is really going to decide for you what you should be learning. Another thing that is going to influence the decision is are you a beginner or a seasoned programmer?

Myself I use ASP, JavaScript, DHTML, XML mainly because all the servers that I use are Windows Servers so it works well and there is no need for PHP or Perl (though knowing perl can help with expressions even in VBScript and JavaScript) since I can do it all without them.