Hi Ashley.
Sorry I was just to tired to continue,

Where were we,
Yes turn XP firewall back on, Then click on the blue link I gave you, that will
walk you through configuring XP/FW correctly.
ATT yahoo internet, Can you give them a ring, Ask if they filter P2P traffic.?
Im looking, but cant find anything yet about them I will get back when I find
something.
AAARR !! Its "AT&T yahoo" Not ATT, and yes they do Block P2P,
Do a L/W search for AT&T yahoo, at the top of this page, Its seems its not all of the time so there may be a workaround
suggested.