Internet Information Services us running in 32-bit emulation mode.

You may get this error during MOSS or WSS installation on 64-bit Windows Server:

Setup is unable to proceed due to the following error(s):

Internet Information Services is running in 32-bit emulation mode.

Correct the issue(s) listed above and re-run setup.

To fix the problem disable 32-bit support in the default application pool settings.

From IIS Manager -> Application Pools -> Set Application Pool Defaults, set the "Enable 32-Bit Applications" to False.

Or run this from your Intepub/AdminScripts folder

cscript adsutil.vbs set w3svc/AppPools/Enable32bitAppOnWin64 1

http://support.microsoft.com/kb/905854/en-us