Windows Security Question

I've been working on mainframes for 30+ years and therefore understand
security which basically comes donw to " If I have a userid and
password for
a mainframe system I can logon and access files that I have been
permission to access".

This doesn't seem to be the case for Windows Security so I am very

This is my situation. Home LAN. I am defined on all systems with
userid of
GOVARNEY with administrator authority. The passwords on all systems
are the
same. Systems are mostly XP Pro with 1 Vista Home Ultimate.

I am on system 1 and map a network drive to the C drive of system 2.
As I
understand it the userid and password of system 1 is used for
on system 2. Given they are the same I thought I should have access
to all
files and directories that GOVARNEY on system 2 has access to.

This is not the case. Why ?????