Which program is it you are wanting to use? Limewire can be set up to use any port you like. I would first off recommend changing the default port. Some ISP's automatically throttle back bandwidth to certain ports. Change the port in Limewire to something like 40000 and then go to your firewall and forward that port and give Limewire full permission with Mcafee. Then make sure that windows firewall is turned off. Go to your network connections screen in xp and right click, go down and disble xp firewall for your internet connection. Sometimes you turn off the firewall but it is still enabled for one specific connection. Tell me what program you are wanting to use and I will try to help you out as much as possible.