Do you need an IDS?

If you have PCI requirements or just want to have a consolidated host based IDS system, you should check out OSSEC at http://www.ossec.net

From their website: OSSEC is an Open Source Host-based Intrusion Detection System. It performs log analysis, file integrity checking, policy monitoring, rootkit detection, real-time alerting and active response.

It runs on most operating systems, including Linux, MacOS, Solaris, HP-UX, AIX and Windows.

It’s open source and available for free. There’s commercial support available for a fee.