cscript.exe adsutil.vbs set W3SVC/AppPools/Enable32BitAppOnWin64 1
Here 1 refers to true.
Then you need to run aspnet_regIIS -i found under framework v2.0.
Fore more information refer
If you are still trouble shooting with IIS, post your thread at http://www.iis.net/ you can use your windows live ID to login or create new account.