Please follow the given steps to configure the web.config file.

                                          

1. Obtain and install "ASPAJAXExtSetup.msi"("ASP.NET AJAX 1.0") on server. 
2. Obtain "standalone.sforce.zip" file from Enzigma and copy to server. 
3. Extract "standalone.sforce.zip" somewhere on Data driver of server. 
4. Obtain streams.exe from TechNet and in elevated command prompt run the command 
    "streams.exe -d -s f:\%extracted sforce folder%\*.*".This"unblocks" the files from having limited capabilities. 
5. Add following code to web.config before </configuration> in the folder. 
   <runtime> 
   <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> 
   <dependentAssembly> 
   <assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35"/> 
   <bindingRedirectoldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/></dependentAssembly> 
   <dependentAssembly> 
   <assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35"/> 
   <bindingRedirectoldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/> 
   </dependentAssembly> 
   </assemblyBinding> 
   </runtime> 
6. In IIS7 go to default website and "Add Application" linking to the extracted sforce folder. 

7. You should now be able to browse to http:\localhost\sforce