Restrict access in drives to others

I want to hide my drive c: from the view on My Computers. I have some personal and sensitive data on the drive which I don’t want my 14 year old son to access.
Not only cannot be viewed but shouldn’t be accessible either through any browsers like IE or Firefox or Google, windows explorer.
Even searching files on it shouldn’t be shown like it doesn’t exist.
Only I can access it either through some password or some key combination with a password.
Is this a registry issue or software solution?
If a software application is there a free version for this?
This is an XP Windows Professional OS.
