MOSS 2007 setup program may crash on 64 bit Windows 2003. You can get the following error message: Setup did not complete successfully. We are sorry for the inconvenience. If it is happening with you then just check one thing: Open Terminal Services Configuration. Click Server Settings. Right-click Permission Compatibility, and then click Properties. Select the Full Security check box, and then click OK. Now you should be able to install MOSS 2007. Please note that directly changing the Terminal Services Configuration settings can be dengerous. So, be very careful before changing.
In 64 bit Windows 2003, you may need to change the emulation mode of IIS depending upon the cases and conditions. To change the IIS emulation mode to 32 bit to 64 bit and vice versa, do the followings: Open command promp and run the following command cd C:\Inetpub\Adminscripts (I am assuming that C is your windows drive) cscript adsutil.vbs set w3svc/AppPools/Enable32bitAppOnWin64 1 (to make it 32 bit) cscript adsutil.vbs set w3svc/AppPools/Enable32bitAppOnWin64 0 (to make it 64 bit) iisreset