For anyone who just got on the bandwagon with Modern Warfare, here's a good way to catch up. Activision is releasing Call of Duty 2, 3, and World at War in one package for 59.99. Pretty nice deal if you missed out on these. Releases in June.
http://xbox360.ign.com/articles/108/1088334p1.html
http://xbox360.ign.com/articles/108/1088334p1.html