I use EastWest/Quantum Leap for the chords, it comes with a number of recorded chords with velocity sensitive and different recordings.

So if you just tap the key, it'd be a chug, if you hit it good, it's a full strum, and there's about 4 or 5 recording of each chord all together. It's a magnificent piece of software.

They also have a new program out, "Ministy of Rock". I'm looking at purchasing it soon, it sound ALOT better than this :)

Cheers :)