iCal deleted after Snow Leopard to Lion reinstall

I couldn't find iCal I reinstalled Snow Leopard, and then updated to Lion. I was deleted somehow. I attempted a reinstall from the Snow Leopard install DVD under optional installs, but it was greyed out and would not let me. I then used Pacifist (after reading other threads on Apple Support Communities) to extract the iCal application, and reinstalled it. But now a message pops up when I click on it that says it will not work with this version of OS X, and that I have version 4.0.4.

How do I get iCal back for Lion without having to reinstall Snow Leopard, or Lion? It says all software is up to date when I attempt a Software Update...