Not sure if you realise but the soft synths you mention actually play on hardware not just software, and in operation are no different to Arranger Keyboards.
The Reason you notice the difference is because normally the sound processing cards in high-end computers tend to be of superior quality. All the sounds produced by modern Arranger Keyboards are done in software, but unlike computers they are stored in Rom. (The latest instruments however now come with or have the option to fit a hard drive)
The main exceptions to this are companies like Wersi, Korg (Oasis) and Lionstracs which are computers with all the keyboards and controls built in, which is why as well as there own voices, they can use a combination of Akai samples, Giga Samples, VST Plug-in etc.
When it comes down to the final analysis however, no matter how the sound is produced, if you don’t like the sound of it, then you are never going to be satisfied.
So just use whatever you enjoy and enjoy yourself.

Bill



[This message has been edited by abacus (edited 11-04-2005).]