Power User Accts: strange behaviours

I'm running XP-Pro (SP2).

Have elevated a couple of accounts from User to Power User by using the
Computer ManagementGroups console and adding the accounts to the
Power Users group and removing them from Users (this was done because I have
read in _SO MANY_ different places that if an account belongs to multiple
groups with different rights and permissions, then the MOST RESTRICTIVE
permissions are what get applied; Since I want the Power User account to NOT
be limited to the priviledges of a mere User, it makes no sense then to keep
the Power User in the User group; _YET_... I have read in some other places -
even this Forum: "Promoting an user to a power user" dated 12/2/2004 - where
the advice offered seemed to ignore the "Most Restrictive permissions" rule
mentioned above. Clarification on this apparent contradiction would be most
appreciated, as well as what I have outlined below.

I am noticing a few strange things (questioning whether this elevation was
done properly, or whether XP is working correctly):
a) when I open Control PanelUser Accounts, the PowerUsername shows the acct-
type as "Unknown" (if Power User is a legitimate local group, shouldn't XP
"know" what it is?)
b) While logged in one of these Power User accounts, I am NOT able to create
a new USer acct (a priviledge which I understand that a Power User is
supposed to have)
c) I use a 3rd party CD-burning software (Nero 6); I *have* installed and run
their special "Nero Burning Rights" add-on tool that creates a special
local XP group which is supposed to identify to XP all Authenticated Users
who can burn CD's (e.g. allow them access rights to "...the lower-level
drivers [this according to Nero website documentation]" normally denied
by XP). However, even with the Power User accts in question having been
added to this group, only the members of the Administrators group are able
to burn CD's - or erase them.

One of the specific quandaries I have which I would like a definitive answer
to should anyone _know_, is:
Is there some kind of obscure "switch" (/?=SecurityGroups...) that has to be
set when SETUP.EXE (to install XP itself) is run that enables/properly-
activates additional XP security groups (besides Users and Administrators),
and that in my case _that's_ why XP shows the Power USers accounts as
"Unknown account types" - because XP wasn't configured properly at Setup in
order to recognize the Power User account type?

Thanks in advance to all Respondents!

--
Patience is a virtue...which one exercises only when needed. Therefo
practice every chance you get....
Computers will give you a LOTS of chances!