Admin now has two names (newcomer to Vista)

Hello all,

This might be sucking eggs for somebody out there, but I'm a little baffled.

I've just purchased a shiny new ThinkPad, loaded with Vista Business.

The sales person had already unpacked and set up the OS, naming the machine
and creating a default admin user.

As with XP when first setting that up, I proceeded to rename the Admin
account to my own name, then add another couple of standard accounts for
family members.

All this worked fine, but when I have a file-system level browse through the
PC I see the directory structure and user name is still 'myt61', the name the
tech/sales guy had used at setup.

SO, right now all the shiny appendages to Vista are calling me 'Mark', but
down at at the shop floor this PC still thinks i'm 'myt61'.

The 'Users' folder has a subdirectory for each of the new users I've
created, plus one named 'myt61'. Similarly, the 'Advanced System Options >
Users' dialogue lists me as 'myt61'...even though the shiny new Vista user
admin system calls me 'Mark'.

How can I rename in such a way that this thing actually takes me seriously?

Thanks in advance,


Mark H
London