FluidSynth is an alternative. I've never used it, but others on this forum have.
https://www.fluidsynth.org/

Windows XP is one of the prepared packages, but you may have some extra work to do for Windows 9X. Probably not too difficult; some have got it working on OS/2!
https://github.com/FluidSynth/fluidsynth/releases/tag/v2.2.5

Hi Meatball,

Thank you for your reply. After a lot of searching and experimenting I ended up using TiMidity++ Windows Synthesizer. Officially it supports Windows 95, 98 and ME only, but it works just fine on Windows 2000 as well. After installation the soundfont can be configured in two steps.

1) Copy your soundfont to "C:\timidity\Musix".
2) Configure TiMidity to use your soundfont in setwindrv.exe (bundled with the program).

I am very happy with the result and I think TiMidity++ Windows Synthesizer is a great alternative for VirtualMIDISynth on older versions of Windows. The program can be downloaded here: https://osdn.net/projects/twsynth/

All the best,

Miko, Strahssis

FluidSynth will work on Windows 98, but it requires manual configuration via commands, to pair to the audio system in the older OS. For a 98 system, you are better off using dedicated hardware over software synths, and one of the Dreamblaster products mated to a Waveblaster header on a soundcard works wonderfully. Thankfully, there is a huge pile of 98-XP soundcards that have those, so you shouldn't have too much difficulty finding something that works, unless you are stuck with a laptop.