install postgresql instructions

Hey guys.

Just installed 7.1.3-1, thanx Jason, the README was perfect for a newbie like me getting up and started.

I do have one question though and this is due to my inexperience with cygwin.  Logged in to my win2000 machine as
administrator,I can't 'chown postgres /usr/share/postgresql/data' 

It keeps telling me that 'postgres' is an invalid user.  This only works when I'm logged in to my box as 'postgres'.
Cansomeone tell me if I got something totally configured wrong with cygwin?  Or am I just not understanding something
here?

Roy.