Well, I've had three or four Wrox books and I've liked every one. So, opinions being what they are... But PHP 4.x has been out for a while now. You can still learn a lot from a PHP 4 book. But since PHP 5.x offers some new features, why not start with the latest?
Beginning PHP 4 came out in 2000. A lot has changed in web development since then. PHP4 has been with us a long time now.
I'd probably go with
this one, which someone else mentioned.
There are a lot of Sams books that I don't like, but Ben Forta (who was one of the inventors of ColdFusion) is a good writer and his SQL book is really handy. I know two other professional PHP-coders who swear by it. You'll get some SQL in most any PHP book, but having a reference is handy.