Stumbled upon that just before checking here,
. Thanks for the suggestion though. After that hunt I'm using a beta of a software synth called Wingroove. Still sounds funky but in an entertaining instead of ear-piercing way. If I wanted to look for the Yamaha ones would I be looking for their soundcard drivers? (Sounds like a very n00b thing to ask, sorry.) That's what comes up when I search.
ETA: More n00bness. Do softsynths always use their own soundfonts or do they use the default gm.dls?