If you want your computer to send information OUT to another server, so you can access the information on it, you don't have to open a port on your computer that is processing and sending the info. By default, anything can go out from your PC, but people won't be able to come in.
I am planning on running a web server on my Windows XP machine. My computer is used to process information all day and I would like it to post results on its progress on the internet for me to check up on it. I am going to use Abyss web server. I haven't done much research yet but I think Http uses port 80 so I will have to open that up on my firewall. I also have port 3389 open for remote desktop use. My question is will running a web server with port 80 open make my computer vulnerable to attack? This won't be a public web site (it won't be listed on search engines) but I have heard that hackers scan IP addresses so that doesn't make me any safer.