You're not going to be able to get away from MIDI, as any software synthesizer, no matter how sophisticated, is going to be rooted around a MIDI core. Don't, however, confuse the cheap MIDI synth on your soundcard as being the "sound" of MIDI in general.
The short answer is, there's no really good way to get a "program" that will make realistic instrument sounds pop out of your computer. If you value realism more, use something sample-based, like a soundfont. If you're looking for control, buy a hardware synthesizer - if your DAW is decent, it'll be able to act as a MIDI hardware host.
As for what program to recommend - it really doesn't matter - I'd say go with the one you like the interface of the most, as long as it supports VSTi. Hell, even FL Studio would do you, if you're okay with track-at-a-time recording.
Finally, you may find
KVR Audio useful for VSTi's and more detailed information. The forums there are very friendly.