pasadoble, yes you can do this. You could check some of the discussions on this forum by Rikki and AJ (plus others). They have setup a system that works for them.
In general, you need a SF2 synth, e.g., Livesynth Pro, Synthfont (
http://www.synthfont.com/ ), etc. You need a host for VST or DX instruments and effects. If you want reasonable quality you would need an external soundcard (M-Audio, RME, Echo, etc.) and hard drive (streaming large samples).