The only thing I'd add is start working on this today!
If you want to know why, start adding up the cost of not doing it. How long will it take you to recreate your build server if it dies? I've seen everything from 1 hour to 3 days or more. Assuming $100/hr burden rate and a team size of 5 that can result in a $100 cost (1 person, 1 hour, nobody is blocked) to $12,000 (all 5 people are blocked for 3 days).
You can imagine how the costs can escalate if your source code is sitting on a file server somewhere or even worse on the programmers box.
Now go calculate your opportunity cost. At one company I worked at the finance department calculated the opportunity cost for the development department was $550 per hour per person! Show that number to the CEO and the head of IT and find out how quickly support requests get resolved.
One final note: if you are relying on your people working overtime to overcome these types of issues consider how you might act differently if you had to pay for that overtime out of your own pocket.