Stability means:

• Up to date software, and operating system
• Up to date patches for all software on the system
• A stable, commercially viable hardware platform
• Good backups, and a validated restore process

Security means

• Good virus protection that covers real time threats, email threats and computer hacking
• Adequate firewall protection at the gateway to the internet and at the machine itself
• Up to date patches
• Using supported hardware and software
• Adequate disaster recovery
• Using complex passwords
• Being extremely cautious about all email content