Another OS.
Windows 2000 isn't DOS-based, and uses NTVDM (NT Virtual DOS Machine) to run DOS applications. It's not possible to get actual sound card working in this environment, because it's basically connected to real PC, not to that Virtual DOS Machine, limiting you to whatever virtual hardware (some Sound Blaster?) Microsoft decided to add there.

You could perhaps consider setting up a a dual boot system with Windows 98SE & Windows 2000 Professional.
Windows 98SE is much more compatible with older DOS titles and you also have the option to boot directly into MS-DOS.
Just be aware that a P2 might be too fast for older DOS titles which means you have to use slow down utilities like Setmul.

Are you talking about DOS games or Windows games? For DOS it will be necessary to go to at least WIN98 because it doesn't use NT VDM. If you are using Windows games, I would still say to use Windows 98, that game can have some compatibility issue with new os's driver thus not displaying the sound card.

For people who don't know, old Sierra games had a sound test that would play a music in case a sound card is detected, on Windows. What I can understand is, the detector doesn't work on old Sierra games with Win2K

Use scummvm (windows 95 ver should work), dosbox, or vdmsound.
Also maybe soundfx but I never used it.
Also setup a dual boot with dos or 9x

Thx for the tips!
Was hoping not needing to change the OS since all other drivers works so fine with the 2000.

If running dosbox, would there be any problem with installing drivers for my Yamaha soundcard? Not used dosbox for ages, so need to get it dummed down and made simple :p
How about MUNT? Do I need it in dosbox to use my Mt-32?