well there's a couple ways to do it
depends on what your parents won't bitch about and if they're computer illiterate or not
1: you can hide the folder. (right click on it and go to properties and click on 'hide this file") then, just go to tools menu, click on folder options, then click on the view tab. in there will be an option that says 'do not show hidden files and folders'
2: creat your own username(windows xp has user accounts for sure, not certain about other OS's). then, put a password on it. move your picture folder to your user's documents, and when on your username, right click on that folder, click on properties, then click on the sharing tab. in there will be an option that says 'make this folder private'. then, in order to access that file, you'll need to be logged onto your username
my advise, do both. a little extra security
also, make sure to go to the search option on your computer, click on the 'all files and folders' option, then click on 'more advanced options', and make sure to take the check mark out of 'search hidden files and folders'
see, i had some stuff i didn't want my wife to mess with, but i forgot about that part, and she was searching for something for some odd reason and found my files. ended up messing with them and totally messing up the way i had them organized
hope that helps ya out