I did get the log-in page to load, after consulting the Leopard Finder "Help" menu. An Apple support article was listed that had the solution. An excerpt follows:
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If you installed Mac OS X 10.5 via an Upgrade Install (the default type), follow these steps:

Open TextEdit.
Click the Format menu and click Make Plain Text. Then click OK.
Copy the below text as is and paste it into the TextEdit document.


Options Indexes MultiViews
AllowOverride None
Order allow,deny
Allow from all


Replace the word "myname" with your user account's shortname. (This is the same name as the user's Home folder in the Users folder.)
Save the TextEdit document on the desktop with the name "myname.conf" where "myname" is the shortname.
At the prompt, click "Use .conf".
Quit TextEdit.
In Finder, from the Go menu choose Go to Folder.
Type in: /etc/apache2/users/
Click Go.
Drag "shortname.conf" from the desktop into the Finder window for (/etc/apache2/users).
At the prompt, click Authenticate.
Enter the administrator username and password and click OK.
Close the Finder window.
Open Terminal.
Enter this command on a single line, followed by Return:

sudo chown root:wheel /etc/apache2/users/shortname.conf
Enter your administrator password when prompted.
Quit Terminal.
Open System Preferences and click Sharing.
Uncheck (deselect) Web Sharing to turn it off, then check Web Sharing to turn it back on.
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This got me to the log-in page, but the default user name and password were not accepted, so I'm still stuck.