Wallander NotePerformer (www.noteperformer.com) is indeed amazingly good but it only works with Sibelius 6 or 7 (also Sibelius First). Alas you cannot use the sounds outside of Sibelius. However it is a fantastic piece of software and you simply write your score into Sibelius and it NotePerformer plays it back really well. It reads all the subtleties of dynamics and switching strings to pizzicato from arco etc etc brilliantly and the more detail you write into the score the better it plays back. It sounds heaps better than the supplied Sibelius sounds to my ears.