Combine two PDF files

I have two PDF files. I want one PDF file. One ends, and on the next page the next one begins. Anyone know an easy and preferably free way to do this?

Edit: Nevermind, Google has served me well. If anyone happens to know a particular program that is REALLY good for this stuff, it’d be welcome, though.

For web stuff, I use FPDF (www.fpdf.org).

your link is mangled.

Thanks – the forum software did a number on me, there, with auto-linking.

*** warning - Mac pimping below ***
I do this regularly on my Mac boxes without extra software. Just an automator action that uses the built-in display PDF engine and the preview app. Sure you could do the same (if less prettily) with open source PDF tools on windows, assuming that your PDFs to be combined aren’t encrypted
*** end Mac pimpage ***

I hate PDFs that have DRM.