Ranging From Permissions To Admin Accounts

First part deals with file/folder permissions.Heres what I would like to do. I have this external hard drive where I would like to have three folders: an archive folder containing old documents and e-Mail, an music folder, and a backup folder to where backup software would create timely backups of documents, e-mails, etc.Is it possible to setup permissions so that the archive folder and music folder were read-only to local and network users and only full access (read, write) to the sys. admin? For the backup folder, is it possible to again only allow read only access for users, and allow read, write access for my backup program and sys. admin? I remember in Windows 2k there was a setting in the control panel (I think it was called Users) and in there, when creating groups and users, a sys. admin could put checks by what each user was allowed and not allowed to do i.e. write, read, etc. However, I do not see this feature in my Windows XP machine (its the Pro version.)My other question deals with Administrator accounts. This question actually comes from ideal curiosity, not an actual problem. I know that Windows, by default, setups up an Administrator's account and is only accessible through safe mode, however, I know there is a registry hack to have it show up on the welcome screen. Any who, is this account any different than an administrator I setup in the users control panel? If its not, then why does Windows make you create another administrator account, so that in the end you have the default one and one you create yourself? My thinking is if they are the same, then that's like creating two root users in Linux. If they were different, that would make a bit more sense. Kind of like in Linux, having a root user and a super-user. The super-user having some power while the root has full power.