After installing WordPress (WinXP, IIS 5, MySQL 5.0.21, PHP 5.1.4) and going through the install, after logging in for the first time I got the error: "Directory Listing Denied".
This was because IIS had not been configured to look for a default document called "index.php".
To fix:
- Go into IIS admin
- Right click on the root dir where wordpress resides
- Select the Documents tab
- Click on Add...
- Enter index.php and click OK.
Then you should just need to refresh your WordPress page in the browser.
HTH
Tim