Confused! Options

[macmonkey]

I've posted questions on here before and you've been helpful, but every time I try and "break into" music software I just end up in a confused mess because it's all 'new ground' for me.

What do i want?

Well, I have a good electric piano midi interface, & a powerbook.

But I want to have more sounds available to me when I'm playing (just at home - not live or recording).

i know that keyboard plyers USED TO simply plug into a sound module which added more 'voices' to their instrument... and that is kind of what I want -- more funky basses, clavinets and synth sounds for starters. But surely software is the way to go rather than forking out for a sound module that will be outdated very soon.

Anyone, know what it is that i need?!

thanks guys

paul