Hi everyone I am new here and want some guidance

My goal is in a couple of months to be able to have a card in the back of my computer and be able to use that to make calls. Some questions I have are, what kind of Linux do I use. Once I get Linux do I just install Asterisk and will automatically start. What kinds of phones do I use. Where do I start. I have a 1GB ram computer w/ vista home premium and 2.66GHz intel core 2 duo. Is this good enough to have a card in the back. WHich cards are good. Analog is the cheapest so which analog cards are good.

Thank You