Well for strings vst's I found out that the expensive packages sound so much better than all these free ones. I had Hypersonic 2 from Steinberg, some great string sounds in that one. Also Vienna Symphonic Libraries and EastWest Symphonic Orchestra are really good! You could also get yourself some other more cheaper Kontakt libraries.
I really like Edirol Orchestral. Got some amazing string sounds in there, alongside a full orchestral symphony, from Cello's to Bassoon's, Viola's to Frenh Horn's!
Here's a quick demo I threw together in a couple of minutes. I havnt done any EQ work on here, these are just basic sounds. Everything done in Edirol