Let us know how you like Opus1 once you have used it a bit. I have a few sample libraries (EWQLSO Silver and Gold XP, KHSO Emerald), but two I have not purchased (if I even need them) is Vienna and Sonic Implants (now called Sonivox) - that I have been looking at with keen interest. GPO is also something I am looking into for solo instruments.
Good luck with Opus1. From what I hear it is outstanding.