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...
Siege of Madrigal
Level: New Alexandria
Follow the instructions to complete the DJ brute easter egg. Once you have seen the DJ Brute, fly to the roof of the Club Errera building and under an air conditioning duct, you will find another switch. This switch will change the song inside of the club to the Siege of Madrigal, a song that has found it's way into Halo CE, Halo 3 and now Halo Reach.