If you're using Visual Basic 6.0, Visual Studio 6.0, Office 2000, or Internet Explorer 5.0, ADO is already installed. However, your customer's system might not have ADO installed, and if it is installed, then the chances are pretty slim that system is running the same version of ADO as yours are. If you don't control what version your customer installs on its system, your ADO application might not work very long. Unfortunately, if the customer visits the Microsoft Windows Update site and decides to download a patch, or a new application, or simply upgrades Internet Explorer, it might end up with a newer version of ADO. So you can't depend on keeping an older version (or even a current version) of ADO in place on the target system—even if you hide it in a locked closet.
So, is there hope for all us ADO and COM users? Well, Windows 2000 technology is supposed to come to the rescue. In the latest version of MSDN News (January/February 2000, http://msdn.microsoft.com/voices/news/ ), there is an informative article that makes me think the problem is at least being studied. The article, "The End of DLL Hell," suggests that the new Windows Installer technology and Windows File Protection will prevent accidental (or intentional) damage to DLLs. What it does not say is whether ADO is considered to be one of the specially protected system DLLs. At this point, there's evidence it's not—but this might have to change.
Windows 9x Users: DCOM95 for Windows 95 must be installed before installing MDAC 2.0x or 2.1x. MDAC installs components that rely on DLLs installed by DCOM95 to register correctly. DCOM95 is not required on Windows NT 4.0. In some cases, DCOM may not be installed on a Windows 98 computer. DCOM95 for Windows 95 is available for download at http://www.microsoft.com/com/tech/dcom.asp.
Sometimes you will want to handle the installation of Mdac_typ.exe yourself. Here's a tip. To use the underdocumented feature that installs MDAC "hands-free" on a user's machine, try these option flags:
Mdac_typ.exe /q /C:"Setup QN1"
While this is not a "quiet" install, it does the job and shows users what's going on (as if they really cared).