Saving Log Files (IIS 6.0)
By default, IIS creates a new log file for each Web site in the systemroot\System32\LogFiles directory. However, you can specify the directory into which log files are saved, and you can determine when new log files are started. To protect logged data, set appropriate Access Control with IIS 6.0 on the log file directory. Consider allowing only the administrator and the IIS_WPG group to have access to the log file directory.
You must be a member of the Administrators group on the local computer to perform the following procedure or procedures. As a security best practice, log on to your computer by using an account that is not in the Administrators group, and then use the runas command to run IIS Manager as an administrator. At a command prompt, type runas /user:Administrative_AccountName "mmc %systemroot%\system32\inetsrv\iis.msc".
To set options for saving log files