Brick wall suggests a firewall. Either your software firewall (XP firewall), else your modem/router's NAT which behaves a little like a firewall.

After trying the suggestions in the link in my previous post, check User Cant Connect - LimeWire

Would be great if you could find out the brand & model number of your modem/router which is what your internet connection passes thru to your internet service provider. It's usually a small box which connects to your computer, so check where all the wires lead to your computer.