I have a Windows NT 4.0 Server with NTSP5 and SQL Server 7.0.2. I inserted the MDAC 2.6 object into the installshield and it copies (I see it occur during the install). However, when I check the msado15.dll version in the Program Files\Common Files\System\ADO directory, it is still the previous version (MDAC 2.1).
If I download and install the Microsoft MDAC 2.6 setup, it works fine.