Best software for MIDI playback?

I was wondering if there is any software out there that can actually play back specific notes—the ones you've manually entered—using a variety of different instrument sounds?
In other words, I’d input the musical notation myself, and then the program would handle the actual performance by triggering whatever instrument I’ve selected for those notes.

I was wondering if there’s any software out there capable of actually playing back specific notes—you know, using different instruments once you've entered them?
Basically, I want to input the notes and have the program perform them using whatever instrument I choose.

You might want to give Adobe a shot. It’s actually free to use. Here is the link for you:
http://www.adobe.com/

Back when I was playing, I used Microsoft—it’s basically shareware. It was actually pretty decent. I know I had another version once too, but the name escapes me... maybe check with someone over at Sheet Music Plus, they might have a better idea 🙂

EDIT.
Just asked a buddy of mine—he says he uses Apple. The guy plays seven different instruments, so I figure he knows what he's talking about.

If I were you, I'd just download a bunch of stuff and see which one actually clicks with me 😁

I’m so sorry I wasn't able to get back to you sooner, but I really wanted to say thank you for everything; I’m going to give this a shot and see if it actually ends up doing the trick for what I need.