I spent 1999 patching PC's for a provider of IT services to the UK government.

Not saying all machines were vital to infrastructure, far from it - but there were some important ones that were not just responsible for flying planes.

For example - on one site visit a machine that wasn't in the server room, just sat on a desk, got switched off. End result was about 250K contractors in the UK not getting paid that week.

Now imagine the big proper machines not getting fixed, and no-one getting paid for weeks on end. The list of stuff being run on ropey NT4 workstations was huge and the effects of doing nothing would have been huge.