"The high notes squeak like a dying cat." Solution: That is actually realistic (violins squeak when played badly), but for production, lower the "Key tracking to filter" in your player, or apply a gentle low-pass filter above 8kHz.
Polyphone (Free, cross-platform).
A patched violin SF2 will never replace a live player or a $600 modeling synth. However, for and 5MB of disk space, a properly patched SF2 offers 85% of the realism for background strings, pop intros, indie folk, and game music. It excels in a mix where a dry, thin, or unresponsive soundfont would collapse. violin sf2 patched