Here is an interesting comparison of Cortana over the course of the 4 halo games:
PTesh adds his dulcet prepubescent tones over the top of one of the new trailers for weapons...
Try upgrading your browser to Google chrome (you wont regret it). There is probably an IE...
Level: Tsavo Highway
This egg is right as you come up the the 1st large bridge (right after you destroy the shild with the drones inside) once you reach the area where you first come out look behind you and up and you will see the sign that reads "Checkpoint 8". It also just so happens that there are 7 checkpoints leading up to this area, so its saying the 8th is just up ahead.