I am new to port scanning and all those types of things and I trying to learn as much as I can about internet and network security, I have a copy of XP that I got yesterday and have done some port scans on it to test the build in fire wall and it shows open ports, how can I found out what these ports are:

135 DCE endpoint resolution
1025 Network Blackjack
5000 ?

I dont know what these results mean, any help would be great.