The Sims and our XP... Help!

Okay, so I've installed the Sims, the Sims Makin' Magic, and the Sims House Party in different orders at different times with different combinations and EVERY TIME I try to run any of them I get a message saying something to the effect of "administrative priveledges necessary to access this."
I tried the official Sims tech support, and they gave me some thing to try (make sure system's on mode where no more than one account can be logged in at same time, manually uninstall and then reinstall) which didn't help at all.

Computer info (as taken from window):
Microsoft Windows XP
Home Edition
Version 2002
Service Pack 1

Dell DIMENSION 8400 Intel
Pentium 2 CPU 3.00 GHz
2.99 GHz
512 MB of RAM

 

you need to install the game as an administrator and enable (if the installation asks you) the game to be used by anyone not just you.

 

Tried that. All the accounts on our computer are administrator. We even set up a new one to make sure.

 

try logging in as login: administrator Password: (none,default).

 

Been awhile... we went on vacation...

Our accounts are all administrator, and I think only one of them has a password, and I know for certain that the account on which the game was installed has no password.