Free VSTi sfz player (Multiplatform):
[UPDATE:] I now recommend using sforzando as your default sf2 player and using the internal engine to convert your sf2's to sfz's. Unlike the two alternatives listed below, it is well-supported and not terribly buggy.
Free VSTi SoundFont(sf2)/sfz player (Windows):
I recommend using sforzando, as above. However for legacy purposes the following is provided. In my experience SFZ, even in it's multi-core version, tends to cause horrific static, so be forewarned:
- sfz - Dual-core/Multi-core/hyperthreading version (somewhat buggy)
Synthfont is more advanced than sfz and can handle one soundbank to every MIDI channel, but has almost double the CPU usage. It also plays GigaStudio files. I have found it to crash Tracktion, but YMMV.
Free soundbank convertor:
- Chicken System's Translator Free
Has some limitations, but can convert soundbanks from one format to another seamlessly.
Often a good way to utilise free Gigastudio/Kontakt files is to translate them to rgc:audio's sfz format, then use the sfz VSTi above to play them. Low CPU usage, and free.
Sf2midi is often the fastest way to find the kind of SoundFont you're looking for, requires free, painless registration.
Realtime Midi manipulation VST's
I have personally found Tobybear's Midibag VST plugins to be absolutely life-saving for MIDI-manipulation. The humanisator, in particular, comes in handy.
Another one is NiallM's ndcMIDI Pack.