Nicki got me Call of Duty 4 for my birthday. I just got around to playing it because I have been so busy. It is awesome!!! This is absolutely one of the best games I have ever played. The graphics are out of this world! Josh has a very accurate review from November on the game here.
I rented it and beat it over the course of two or three days. It was a great, great game and the multiplayer is a blast. The single-player game is only about 5 or 6 hours long, but the multiplayer extends the replay value considerably.