Please, can you explain how you managed to add a user to "Everyone" user group on Windows XP ? As you said, the workaround worked for you aslso on that OS but as far as I know, "Everyone" is a special group in WXP without the ability to accept real users.
Believe or not, this wmware tools instalation critical issue is still not resolved in lates vmtools 10.0.x
Thanks,
David