I booted up a machine today that hadn't been booted since August of 2003. It had Windows 2000 installed, and the first thing it did was complain that another machine on the network had the same IP address, so it shut off its network connection. After some hastle, Brian and I got it on the network.
Here's the punchline: within 5 minutes of connecting to the internet, the box contracted Sasser. Argh! Can't Windows stay useful for 5 minutes?! Brian warned me that Windows computers that haven't been updated can get Sasser in under 10 minutes when connected to the internet, but 10 minutes is barely enough time to patch the dink thing!
All of that to say, avoid using Windows for more than five-minute stretches; it might come down with the plague.