Example 2 — Customizing the logo on your team Web sites
To customize the logo used on new SharePoint team Web sites, do the following:
Open the Program Files\Common Files\Microsoft Shared\web server extensions\50\Templates\1033\Images directory.
Copy the image you want to appear on the home page of your team Web site to this directory.
Delete the SharePoint Team Services logo HOME.GIF.
Rename the new image HOME.GIF.
Create a new subweb.
All sites created from now on will have the new image as a logo.