Hi Robert,
barely noticeable. I tested it by midiing up digital piano & playing the keys. Just the faintest echo.

Software was optional with my new dell laptop Inspirion 640m.( core duo , 1.60 mhtz)
"Intergrated Soundblaster Audigy advanced HD Audio" I thought for the additional
$18-00 AUD it was worth getting.

I actually use my own soundfonts with it though, as the 2mb gs set that loads into it by default, can't be edited.
I can remove the default soundset or load individual soundfonts over the top.

Using Forte, Asio4 all etc I ended up with just over 11ms latency, using Forte & the internal drivers 10ms.
Since I'm only using soundfonts anyway, it's just as easy to use the audigy software.

Just out of interest I tried loading the software into my old dell laptop ( just before it died on me again) but it wouldn't recognize it. May have something to do with the 945gm chipset installed in the New dell.

best wishes
Rikki