To my recollection we were told that it would work on any version of Windows (sans 3.1) without the need to install DX.
No, if it was created in B+ it needs DX1 =]
DX1 or higher comes on all version of Windows 98 onwards, Win95 had DX1 included ... well, not in the first major release, but somewhere along the line.
I'm pretty sure a B+ program would not work on Win3.1 ever. =]