Let's Say

Let's say I have two web pages and I only want to
load the one that is the newer of the two.
How can I determine which is newer without loading them both first?
Sort of a load a page and it forwards you to the newer(of the two) page.
I know how to do the forward. Just not the choosing which to forward to.

Of course I'd like to know in the context of using the tools availible here to me as a munuvian.

Can anybody help me?

Madfish Willie? Pixy? Bueller?

Update, the decision part is figured out, now all I need is a php utility/command that returns the date when a file/url was updated.