If you wish to hide a specific task:
1. Start / Programs / Accessories / System Tools / Scheduled Tasks.
2. Right-click the task and press Properties.
3. On the Security tab, press Advanced.
4. If the user or group is not listed, Add them.
5. Select the user or group and press View/Edit.
6. Deny the user or group Traverse Folder / Execute File and List Folder / Read Data.
7. Press OK, Apply, and OK.
The job will become invisible to this user or group.
NOTE: The Run As context of the user must NOT be a member of a 'hidden' group and must not be specifically 'hidden'.