What's critical in any suspected security breach is following a standard process and documenting every step along the way.  If you're like most IT people, you don't necessarily know where to start.  

• Building A Computer Security Incident Response Team
• Developing An Incident Response Policy
• What Is An Incident?
• Incident Response Cycle:
• Incident Life Cycle – Discovery
• Incident Life Cycle – Communications
• Incident Life Cycle -  Containment
• Incident Life Cycle – Remediation
• Incident Life Cycle -  Recovery
• Incident Life Cycle – Post-Incident Review
• Incident Life Cycle – Lessons Learned