Oh well....
Bad news :
I've tried all the Win2k Candidate Drivers, and also tried the naked .inf File with the 1.04.00.
The Result is always the same, regardless of Driver used :
As soon as the Desktop Video Mode is initialized, the entire Screen and the Mouse Pointer instantly become completely garbled, and the machine locks up seconds after that.
Looks like Hank Semenec was right, the Win2k Driver Cores make a DRAM Init (based on SD-RAM I figure), which instantly screws the DDR SDRAM timings.
btw, Win2k would like to see exactly this line in the .inf (to accept an automatic instead of forced Installation) :
PCI\VEN_121A&DEV_000B&SUBSYS_019B1014&REV_01
------------
So that is basically the end of my Possibilities, I only got the Win9x Drivers to work semi Stable, that's it.
The last Service I can provide is the Card's BIOS :
http://www.falconfly.de/temp/Voodoo4-2_4200_Supported_BIOS_v105.BIN(64k)
Maybe someone can generate useful Info out of it...