Protect Folder

HI,

I am having WIN98 O/S. How can I find the Current logon user.
Ofcourse we have to use API. I am not sure about this(accessing registry).
What are the keys to be given. From that i will find the current user and restrict the
folders from delete.

My main aim is to restrict the folder from delete(if the user is not administrator).
Whenever i install this application in any system that will run as a service i.e if the user
presses DEL key automatically it will run this file gives appropriate error message.

Pls, help me in getting this.