0000950123-06-011832 S-1/A 2 20060921 20060921 COMMVAULT SYSTEMS INC 0001169561 7372 000000000 DE S-1/A 33 333-132550 061101680 2 CRESCENT PLACE OCEANPORT NJ 07757-0900 7328704000 S-1/A 1 y24537a6sv1za.htm S-1/A EX-5.1 2 y24537a6exv5w1.txt EX-5.1: OPINION OF MAYER, BROWN, ROWE & MAW LLP