What Causes Latency?, Trying to make sure I have no Latency Options

[manexmachina]

I'm setting up from scratch and the number one complaint I had about my old system (like 6 years ago) was massinve playing latency. I hit a note on the piano and by the time the virtual instrument (sample cell at the time) played back, it was very delayed. I'm not going to erase 20 some odd years of practice and get used to that.

So! how do I avoid it? Is it the software, the hardware, the VST, the audio input, the midi input? What are good combinations? Can I avoid latency on a Powerbook? I'd love to use a 17" G4, but would be willing to buy a dual proc. if necessary.

Specific equipment recommendations are helpful. Preferably recommendations that mention which software they work with best. (Please don't make this into a which software is best thread though, that's not my concern_/

thanks in advance!