Windows x64 IIS 6 running 32-bit App Pools
nternet Information Services in Windows x64 is 64-bit. This means, if you want to run 32-bit ISAPI DLLs with IIS6 on Windows x64, you’ll need to apply a small tweak. Open up a Command Prompt window, and type this command to enable 32-bit Application Pools:
cscript %SystemDrive%inetpubAdminScriptsadsutil.vbs set w3svc/AppPools/Enable32bitAppOnWin64 1
Down the road, if you’ve made the required steps to update your stuff to 64-bit, type the following to re-enable 64-bit Application Pools:
cscript %SystemDrive%inetpubAdminScriptsadsutil.vbs set w3svc/AppPools/Enable32bitAppOnWin64 0