UPDATE:

I have replaced the SB 128 (CT4700) with the SB Live! (CT4760).
Have already test the MIDI sounds, playing some .mid file with different sf2 soundfonts.
With the DOS drivers, this is also supported under DOS box.
It's quite good !!
With the sf2 standard, i can switch between many different soundfonts available in the internet !

Because the CT4700 is limited with the 2M, 4M and 8M ecm files, ... , the SB Live is the much better choice for a pure Win98 system (with DOS box for support of non-Win98 games ....)