You cannot upload files that are larger than 28 MB on a Windows Server 2008-based computer that is running Windows SharePoint Services 3.0

When you run Windows SharePoint Services on a Window Server 2008-based computer that is also running Internet Information Services 7.0, you cannot upload files that are larger than 28 megabytes (MB). You experience this problem even though you have configured the large file upload settings according to Microsoft Knowledge Base article 925083.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:

To work around this problem, follow these steps:

1. Use Notepad to open the Web application Web.config file. By default, this file is in the following folder:
   Microsoft Windows SharePoint Services 3.0
   C:\Inetpub\Wwwroot\Wss\VirtualDirectories\ VirtualDirectoryFolder
   
   Windows Small Business Server 2008
   C:\Program Files\Windows Small Business Server\Bin\webapp\InternalWebSite
2. Add the following code to the <configuration> section of the Web.config file:

   <system.webServer>
   	<security>
   		<requestFiltering>
   			<requestLimits maxAllowedContentLength="52428800"/>
   		</requestFiltering>
   	</security>
   </system.webServer>

   
   Note This code sets the value of the maxAllowedContentLength property to 52428800. Therefore, the maximum file size of an uploaded file is 52428800 bytes. However, set the value of this property so that it is larger than the file that you are trying to upload. Also, set the value of this property so that it is larger than the maximum file upload size that you have configured in SharePoint. If you do not, users will not receive an error message that they are exceeding the size limit if they try to upload a file that is larger than the maximum file upload size that you have configured in SharePoint.
   
   For more information about the maxAllowedContentLength property, click the following article number to view the article in the Microsoft Knowledge Base:
   942074  (http://support.microsoft.com/kb/942074/ ) Error message when you visit a Web site that is hosted on a server that is running Internet Information Services 7.0: "HTTP Error 404.13 - CONTENT_LENGTH_TOO_LARGE"