I managed to get the MPU-401 Microsoft generic
driver back to work like in RC3, go to WINNTINF and
edit the WDMAUDIO.INF remove the line
"ExcludefromSelect = *" and save it.
Then if you go to the add Hardware and add new
Audio Device under Microsoft the good old MPU-401 appears again, only it says it
has no digital sign on it, but simply ignore it. Now my Yamaha SW60XG is back to
work, even under W2K...