connect to network question

I have an Acer Aspire 5100 with Windows vista. I have a wireless network at
home with a Netgear router. To get on the network I have to assign static ip
and dns,gateway etc and it works good. However when I go somewhere that has
public free internet the computer will connect without assigning all that I
have to at home, why? After I use it somewhere as above and come home the
computer has lost all my home info. and I have to set it again. Is there a
way for it to get on my network at home like it does at the public places. If
no, is there a way to keep from having to inter all my info to get on my home
network? I have read everywhere and I think that there might be a way to save
profile and do what I want but I just don't know if that is what it is for or
how to do it. Any help appreciated.
L.D.