I have connected my gear with PC for recording purposes. First step was using a freeware software called Audacity. But I didn't connect my guitar directly into PC. I connected a guitar to an amp, and amp to PC. The main problem with this setup was latency, I was able to hear the notes much later than I've played them. It made playing vere difficult. Then I bought quite affordable M-Audio PC interface, where I can plug a guitar (and other instruments) directly. With the interface came ProTools Express audio workstation. It has enough sounds and virtually modelled amps and effects for my purposes.

For your purposes, if you have an amp, connect headphones directly into it. That's the easiest way to play without disturbing the others.