User accounts, and directories under docs & settings

Hi,

I'm trying to understand how XP Pro handles users, administrators, etc.
and the directories for these accounts.

I have two PCs with XP Pro on them. One was bought with XP pre-installed
and the other had it installed by me (from scratch, not as an upgrade).

On the preinstalled (by Dell) system (call it X) I have these accounts:
Control Panel/User Accounts
John Administrator
Robert Limited
Guest Off
Control Panel/System/Advanced/User Profiles
Administrator
John
Robert
CONTROL.EXE userpasswords2
Administrator
John
Robert
Guest
Directories under Documents and Settings:
Administrator - with the usual stuff (application data, cookies,
desktop etc.) but also has 'Administator's Documents'
instead of 'My Documents'.)
All Users
Default User
John
LocalService
Networkservice
Robert


On the other system call it Y) I have these:
Control Panel/User Accounts
John Administrator
Guest Off
Control Panel/System/Advanced/User Profiles
John
CONTROL.EXE userpasswords2
Administrator
Guest
John
Directories under Documents and Settings:
All Users
Default User
John
LocalService
Networkservice

Ok... (Sorry about the length of this)

My questions are...
1) Why does Administrator have a directory on system X but not on Y?
2) Why does Default User have 'Administrator's Documents' rather than
'My Documents' on System X
3) Why does Administrator not show up as a user under
Control Panel/System/Advanced/User Profiles on system Y?

I suspect that the answer to 1) is something to do with Dell having not
set up any other user account, and just logged in as Administrator to
configure my PC, and hence the 'user' directories for Administrator were
set up. On system Y I don't think I ever logged in as Administrator
(except maybe during install, if it's required) and set up my user
account at the start.
Ok, now another thought occurs. Is the answer to 2) linked to the above?
Maybe it is created by copying the initial users directory during install?

Does that make any sense? If not can you enlighten me?
What about Q3?

Another question... Can I delete that Administrator directory under
Documents and Settings? I can't see what purpose it serves. Or does it
have some use?
Would a similar directory appear once I logged into the other system as
Administrator?

Thanks for any advice,

John


P.S. I can't help feeling that all this multi-user stuff is a little bit
over the top for XP. It's all quite good in a way, but we are talking
PCs here and not servers or mainframes. :-}