I have a Kawai CA63, which I'm very happy with - the keyboard is great and the stock piano sounds are just fine for me. Most of the time I play the piano, but I'd quite like to have access to good historical keyboard instrument sounds too, in particular a good harpsichord and baroque chamber organ. The Roland C30 digital harpsichord is a piece of kit I've always admired, but I really can't justify the price tag. Lately I've been wondering whether the software piano route might be a way to get some some of these sounds from my current DP. As well as harpsichord and organ it would be nice to have a range of instruments - clavichord, fortepiano etc.

It seems there is a lot out there as third-party plugins to packages such as Pianoteq, and I've also found a dedicated organ package (Hauptwerk).

So, my questions are -

Does anyone have any experience of historical keyboard instrument simulations in software, and any recommendations ?

What sort of PC setup do you need - presumably it needs a reasonably fast CPU and something better than the stock soundcard that ships in a laptop ? I'd consider building a small form-factor PC with a solid state drive just for the purpose (to keep the noise down) and it would still be a lot cheaper than a Roland harpsichord.

I'm using Sonivox Harpsichord for a variety of harpsichord sounds. It's better than my Clavinova's harpsichord. It'll run on just about any PC, even my six-year-old clunker laptop.

Hauptwerk for organ definitely.

I have not tried them myself but these ones have always sounded nice to me for a 'solo' type of playing:
http://www.realsamples.net/d_0028_Harpsichord324.htm