Survival time of (unpatched) machines on the 'Net
The Internet Storm Center publishes these cool graphs of the average time an unpatched machine will last on the Internet before being taken over by malware (not even with someone surfing).
Windows machines last just over 100 minutes; "Unix" machines (not sure the OSes they cover) last from 400 to 900. The point being that this is typically much longer than downloading/installing updates will take.
More and more like "Curious Yellow", an essay written several years ago.