i think external sound card is the way to go as you loose all the static from your pc, your pc should be able to handle just about anything so no problems there, software wise if u just want something simple to start with try audacity thats ment to be good and free so you can allways upgrade later.
from what i have read about internal or external soundcards you get what you pay for, you could always buy something like a line6 tonport, they record via usb i think and come with all the recording software and plus you get amp modeling.
that is all good if your only recording oe track at a time, and then mix them later
if you want simultaneous recording your will need a mixer

monitor dont colour the sound, they are designed for flat respose at as many frequencies as possible, your speakers will colour the sound but for starting off i wouldnt say it mattered much.