I'm struggling with the accounts built in to windows xp.  Are the only
options those of making a user either an administrator or a limited
user?

It seems that the limited user is pretty low on privileges, but I'm
reluctant about configuring someone as a full administrator.

Thanks.

Are you using Home edition or Professional edition?  Home edition only
has the two options.  Professional can provide you with more control.

From the Control Panel, open Administrative Tools, then Computer
Management.  Under system tools open Local Users and Groups.  Select
Groups.  These are the built in groups in Windows XP Pro.  You can
also restrict or grant additional access from the Local Security
Policy icon in the Administrative Tools window.