Oh, one other choice if you are even a little bit handy with a soldering iron: you can use the Yamaha Waveblaster daughterboards for old soundcards as stand-alone synths by literally hooking up a handful of wires: power, MIDI in/out, and audio in/out. There's a bunch of DIY projects demonstrating this on the web.
That gets you a huge range of pro-grade instruments, effects (even for external instruments, voice etc via the audio input) and editable parameters (XG being Yamaha's extended General MIDI, like Roland's GS), and practically zero CPU load. All editing would be done in software over MIDI, for which any XG editor will do (there's a few around), or "mixer maps" for your main DAW software (Cubase, Logic, etc).
http://www.joebrown.org.uk/wp/?p=3124
It's proooobably possible to do the same with Yamaha's later PLG daughtercards, but I haven't investigated that. One wrinkle is you would need to add a DAC, as their audio output is digital, whereas the Waveblaster cards give you analog audio straight out of the box. Er, card.
That gets you a huge range of pro-grade instruments, effects (even for external instruments, voice etc via the audio input) and editable parameters (XG being Yamaha's extended General MIDI, like Roland's GS), and practically zero CPU load. All editing would be done in software over MIDI, for which any XG editor will do (there's a few around), or "mixer maps" for your main DAW software (Cubase, Logic, etc).
http://www.joebrown.org.uk/wp/?p=3124
It's proooobably possible to do the same with Yamaha's later PLG daughtercards, but I haven't investigated that. One wrinkle is you would need to add a DAC, as their audio output is digital, whereas the Waveblaster cards give you analog audio straight out of the box. Er, card.