I guess it depends on what you're working hard/talented at, and how your mind works. There are some things - mostly academic, I think - that you don't really need to work hard at if you're naturally good at them, because your mind just works in a certain way; for example, a friend of mine barely attended University at all, and yet he managed to pass with 1st Class Honours, because he understood the subject. Other people worked really hard, and they fell just short of the mark.
But in the case of skills you need to acquire, such as playing a musical instrument, or something like that, I'd probably value hard work a little more than natural talent, because even if you have a natural talent for something, you still need to work for it to a degree, and that takes time - the more time you spend on something, the better you are at it, as a general rule.
I think for most things it really does depend on how your mind works as to whether or not it's better to be talented than hard-working, though. You could work as hard as you wanted at something and still not be able to do it, and just because you're naturally talented doesn't mean to say you're particularly good at it, just that you could be.