Dear Folks --

Thank you all so much for the excellent replies.

I should have specified more clearly that the my intended synth use is mainly for a performance setting (practice jam sessions and on-stage and etc).

I am using a few of the soft synths mentioned above and they work great.

So I take output from my keyboard via USB MIDI and connect to the laptop's soft synth, and as for the latency issue, I have eliminated concern by (1) turning off all other USB port activity, (2) and by tweaking the buffers, (3) and by using Asio4All, and so I output the synth sound from the headphone jack on my laptop to the mixer, and that gives me almost zero latency but not quite zero-- SO-- my final step was (4) to simply send the other stereo output from my keyboard to a local mixer which sends the on-board keyboard sounds (not soft synth sounds) to the mix, so I just pick one of the nice built-in tones (Piano or Organ or Strings or E-Piano or any combo of 2 of these) and send that sound to the mix-- which is never a latent sound-- so the initial attack that fills the latency gap is from the keyboard directly and the synth blends in milliseconds later, so this layering makes latency a non-issue for me, which makes playability a joy, and the sound is awesome IMHO.

If I go the hardware-synth route, then I would probably jump up to something full-blown, like the Casio Privia PX-5s or the Yamaha MM8.

Thanks.

-- Mark Kamoski