While I haven't done "extreme" configurations, it works well with various Sound and Graphics cards. We are talking Windows 98?

I haven't noticed any major dramas.

Yeah 98SE, but I guess the question is relevant for other Windows versions as well. I was thinking about something like multiple Geforce cards where you'd use different driver revisions for each. Or maybe even switching different 3dfx cards.

I don't see a problem there.

Often you can just re-install the driver each time you swap a card. I never had issues doing this. But I can't guarantee that it have some impact somewhere. At least when benchmarking I haven't noticed anything out of the ordinary.

I'd remove the drivers if you have to change versions/type for the new card (e.g. if you're switching from nVidia to 3dfx, remove the nVidia drivers), but if both cards can run under the same driver (say for example you're switching a Radeon 9800Pro out for a 9700Pro) I wouldn't remove the drivers - just switch the cards and the drivers should detect things. If you want to change after the install (e.g. a different version works better with the new card), just do an update or uninstall to roll back from there.

I've never had an issue with this, in general, but ofc we are talking about Windows... 😵

I've used Driver Cleaner Pro in the past for this. Even has dedicated support for 3dfx and some other vintage hardware companies, so the tool is more suited for this than modern PCs where driver remnants should be less of a problem 😀

I just switched a Win98 HDD to a whole new system, at first it complained as it found all the motherboard hardware, but that's to be expected. After that I just installed the new drivers.

Works as well as it ever did.

It is safer to delete the drivers from hardware no longer present in system. You can remove the non-present devices in Win98 Safe Mode. However, I'm just too lazy to do it every time, only doing it in case of problems. Sometimes old drivers really interfere with present ones, especially if they were designed for Win 3.1 but used in Win 98.