PHP is easy to learn, and as for frameworks - why not use one that runs on PHP?
CakePHP is what I use and it's so easy to work with, I suggest using it instead of Ruby on Rails, due to ease of configuration, wide-spread support of PHP and the ease of using Ruby on Rails
When I was in your position I read some tutorials on PHP to get a decent understanding of the language
http://devzone.zend.com/node/view/id/627
Is a good primer.