After many failures to install VS2005 on my laptop, I got a second machine and reinstalled XP (and drivers) in order to bypass any app conflicts. This wiped out McAfee (which was part of the install image), and the XP install turned on its firewall by default in response.
I hadn’t noticed that the firewall was on, and when I tried to get IIS to serve a simple xml file from its doc root (c:inetpubwwwroot), only the hosting machine could access it. Yet ping from other machines to the IP name worked.
I looked in the IIS access log at c:Windowssystem32LogFilesW3SVC1ex*.log, and there weren’t even any access attempts from other machines shown. Googling “The page cannot be displayed” revealed the firewall involvement.
To disable the firewall, Start|Run, and enter “Firewall.cpl” and follow the prompts.