If your company has a strong open source technical team I would recommend taking a look at AlienVault.

AlienVault is a collection of 15 open source programs which can collect data from over 35 different products to help you manage and monitor your network security blanket. The open source products used range from popular ones like Snort (IDS), Nessus (Vulnerability Scanner) and Ntop (Network profiling).

None of these products are new and have been used by many people in this configuration but what I like about AlienVault is the web site presents the products in a manner that is easy for management to understand and gives security professions a good idea on how to present these open source solutions to management.