Set the maximum size of uploaded files

Add the httpRuntime element in web.config as follows:
<configuration>
<system.web>
<httpRuntime maxRequestLength="8192"
useFullyQualifiedRedirectUrl="true"
executionTimeout="45"
versionHeader="1.1.4128"/>
</system.web>
</configuration>
The maxRequestLength attribute limits the upload size. For example, if it is set to "8192", it will be 8M.

http://pyt5208.cnblogs.com/archive/2006/07/10/446994.html