jingler

hi i have 2 computers with windows xp. Both of them are connected to the internet with Static ip 1 mbit. I would like to know how i could connect to them remotely wihtout use any third party programs. I'm trying to connect to one of them but it shows me a window and ask me about to put a password. But at this window i cant put my user name: Administrator.. Its locked to quest..and its asks me to put the guest password. how i will conect to the pc remotely without use other programs.