Good to hear from you. Not so good to hear about the employment deficiency.

So the difference between PHP 4 & 5 ... There's a lot of OO functionality built in to 5 that you had to do yourself in 4. You can accomplish a lot of the same things with less syntax, because whole classes that were parts of common toolkits are now language constructs. I think I'm fairly safe in saying that if you learned 4, most anything you write will work in 5.

The best documentation is the [link|http://www.php.net/manual/en/|online manual]. I'm convinced PHP's popularity is due in large part to the quality of the manual. Chapters 18 & 19 (Classes and objects PHP 4 / 5) sum up most of the difference between the two. Each function (not just in those two chapters) has a reference at the top to which version it appeared in.

You'll probably want some tutorials to get started. There's a good selection on the [link|http://www.php.net/links.php|links page], though I no longer have any idea which ones are current and good.