What are the best web-sites for learning PHP online for free?

As Greg said, http://php.net/ is a great resource, it should be first in your php bookmarks!

Zend Developer Zone should be second on your bookmarks list:

http://devzone.zend.com/node/view/id/627

Also have a look at http://www.sitepoint.com/subcat/php-tutorials

Sitepoint is a great website catering for almost all web development queries (html, javascript, xml, php, asp.NET, perl, ruby, SQL etc...). Check out their forums, I have very little need to go anywhere else, it's that good.

I've definately found that once you get a good grasp of one language, it's easier to pick up a second. I would recommend you learn javascript at the same time as PHP. In doing so, you will notice the similarities and differences in the language structures which will give you a better insight as to how to go about a particular problem.

To that end, I forward these resouces and wish you well on your quest:

http://www.quirksmode.org/resources.html

http://icant.co.uk/articles/from-dhtml-to-dom/

http://24ways.org/2006/writing-responsible-javascr...

http://www.sitepoint.com/subcat/javascript

http://userjs.org/help/tutorials/

Many public libraries have a application referred to as Mango that's very similar to the Rosetta Stone application you spot marketed on TV. It's additionally very well -- and loose. Check your library's internet site.

http://www.php.net/ has everthing you could ever want. Great if you have previous programing experience.