I recently purchased the Virtual Grand Piano from Art Vista(Hans Adamson). It's on sale for $99 until 8/16/05 then it goes up $21. If you are looking for a piano that is better than what comes with a sound library then check this one out. It sounds really great and comes with enough variations that you'll find the sound you are looking for. It's a joy just to play.
It does require a G5 Mac(NI's Kontakt Player) and uses about 6GB of hard drive space. It can be used as a stand alone or a plug-in. It seems to work fine with Metro 6.3.