well I think that if you use encryption, even other admins wont be able to read the content.In XP/2k when you reset a password using a Admin account it tells you that it will remove all the right on the encrypted stuff(happened to me didnt read the notice and theres no way I can access the file now).
So basically right click on the folder advanced, Encrypt data. I think it should do it.
Otherwise theres thousand of programs on the net to put PW on folders...
Asus P4P800DX, P4C 2.6ghz@3.25ghz, 2X512 OCZ PC4000 3-3-3-8, Leadtek FX5900 w/ FX5950U bios@500/1000, 2X30gig Raid0