The reason the header didn't work: If you're going to do something like that you need to make sure it's one of the first things done, else the page will already have sent it's header information out thus producing that error.
It always works unless you've done anything with sessions or cookies (I'm sure there are other similar causes of the error, but these are the two main cuprates I've found).
And no, deadly7. He's saying it's the first routine that should be executed within PHP.
By tradition, meta tags are within the head tags, but it doesn't matter (I think W3C might care, but all browsers I use don't).