restrict user access

A long winded and detailed answer is here:

http://www.microsoft.com/technet/security/prodtech/winclnt/secwinxp/xpsgch06.mspx

The easier answer is to do the following, if this is a stand-alone system:

Create another user account and profile. Place that user account in the USERS group on the local system.

With the administrator account, only give permissions to the certain security groups ie Administrators, power users, etc).

An overview of this process is here:

http://www.microsoft.com/windowsxp/using/security/learnmore/accesscontrol.mspx