By learning PHP, you'll also learn how web programming is traditionally done and the basics of how the web works. Once finished, you'll clearly see how Rails makes certain aspects of web programming easier, even for things like form validation.
I recommend a book like "PHP 6 and MySQL 5" which is very easy to read, and definitely type in the examples! http://www.amazon.com/PHP-MySQL-Dynamic-Web-Sites/dp/0321525....
You have nothing to lose learning PHP. I love Rails, but I use PHP in a pinch. Hell, even DHH said he fired up PHP recently and liked how quickly he could wire up small bits.
Rails is too magical and mystical. If you don't understand the lifecycle of web requests, you are going to be shafted really quickly when Rails starts its magic tricks.
However, if the experts here think that PHP would be a worthwhile detour even though I plan to go with Rails, then I'll go with that. I guess I'd just like some assurance that I can pick up the basics this way and that I can do so in a reasonable amount of time.
Yes, I know patience is a virtue, but I just want to make sure that my time is spent as productively as possible. I do very much appreciate the advice from everyone.
If you're familiar with a C-based programming language, then PHP will be very fast to pick up. And, if you want to "actually be able to build something," with PHP you'll absolutely at least feel like you can haha.
Ruby is a good language for CGI programming.