I once installed Windows XP on a machine that got compromised in the first 20 minutes just because I forgot to unplug the network cable while installing it -- although I wasn't prepared for offline updating anyway.
When a machine gets compromised by just being connected to a network, that's pretty bad and I sure hope Windows 7 is a lot better.
You were doing a fresh install (no SP) of a 10 year-old operating system (xp) on an infected network and you were surprised you got compromised?
Now, XP is first of all, not a great standard in security practices. But without any security updates, on a platform that hackers have had 10 years to find exploits to? If you installed that on an infected network, I'd be surprised if you didn't get compromised.
When a machine gets compromised by just being connected to a network, that's pretty bad and I sure hope Windows 7 is a lot better.