As someone who started with Perl and now does PHP as well, I'd say for what you're doing, PHP is probably the better choice . . . I find it much faster to develop web apps with it. As far as security goes though, for the most part (barring security holes that are discovered in the PHP or Perl interpreters), the overall security of your app is going to depend on how well it is written.
IMHO, I wouldn't start with a tutorial . . . if you find one written for an earlier version of PHP (and the server you are testing/producing on has a later version), you may find some things don't work as you expected. Working with forms and uploading files were two areas that the books and tutorials I initially was looking at provided examples that didn't work in PHP 4.2.
In any case, the book I found most helpful was Mastering PHP 4.1 by Jeremy Allen and Charles Hornberger, published by Sybex. It's available from Amazon at a pretty good price. It will get you started with basic PHP in no time, especially if you've got some background in C . . . the syntax is similar. However, if you do choose to get this book and you're working with PHP 4.2, skip the chapters on form handling, and have a look at the PHP manual (on the PHP web site) for the latest info -- you'll save yourself a lot of grief.
