I have followed the following article to install DotNetNuke on my local machine but get the "Configuration Error" when launch it by typing in the URL http://localhost/dotnetnuke/

http://www.dnnsoftware.com/wiki/how-to-install-dotnetnuke

Here is the full error message:

Configuration Error

Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. 

Parser Error Message: Unrecognized attribute 'targetFramework'. Note that attribute names are case-sensitive.

Source Error: 

Line 123:    -->
Line 124:    <!-- set debugmode to false for running application -->
Line 125:    <compilation debug="false" strict="false" targetFramework="4.5">
Line 126:      <buildProviders>
Line 127:        <remove extension=".resx" />

4.5 is installed on my computer but the App Pool dropdown doesn't have the option to select 4.5; it has 4.0;  and 2.0 in the list.