Free VST Hosts here also Ableton Live (Which comes in entry to fully featured versions) is designed for live onstage use. (Trials are available to see if it suits before purchase)

What sort of VSTs are you looking for? As there are many good free and entry level versions out there.

This site here is also worth putting in your favourites if you want to get into VSTs, not forgetting Synthzone itself.

Hope this helps

Bill