While it sounds terrible, I really don't see the benefit from upgrading your OS if it is running just fine (other then security issues etc.). The OS is not running the airport system, specially designed program(me)s do. As long as they are upgraded and maintained well, that's the big issue?
I recently talked to a ATM repairman who I saw switching a BoA ATM machine. It turns out that the replaced unit was running on OS/2 V3 which is not much younger than W3.1. Other ATMs I have seen in the US and EU seem to still run on MS-DOS.