Read entire post before doing a thing.
Use this guide to set up a static IP address:
Then use this guide to forward your ports:
http://www.portforward.com/english/rout ... rindex.htm
Find your router on that list (you'll need company and model) then follow the (picture filled) guide.
It'll teach you how to foward ports (just click anything in the list of applications, im fairly sure WindomXP isn't there, and the instructions are the same for every application, just change the port numbers).
But before that
, you have to make sure you have administrative access to your router (i.e. know what the user name and password is) or don't bother at all, because you won't be able to alter anything.
(I would also recommend logging into your router and taking a look at "application support" (might be named differently depending on your router) and see what you can do there. For example, my router only lets me put 6 letters into the "app name" field, which means I can't enable ports for pretty much anything.)
Note: Before messing with your internet settings (i.e. setting up static IP): WRITE EVERYTHING DOWN. Every default setting must be recorded so if you screw something up, you can always revert back to get it working again. The guide is fairly straightforward, but it's still better to have someone who knows their stuff to help. Note that if you do mess up somewhere, you will not be able to go on the internet or do anything (which means revert back to your old settings immediately, and try/do not try again). <<>>
That being said, if you're careful with following instructions, there shouldn't be a problem.