mc = my computer
If you know a little registry editing then you could create an account, and edit the registery to block out basically everything.
(Like what some library or school computers have)
If not for that, make a guest account.
If your account is password protected, even if they have access to "my computer" - the hard drive, windows should not let them open your user folder.
If you are really worried - then safest option is to not lend it to them, as there really is no way to not hand them over all your files by lending them your laptop, they could pop out the hard drive, and have access like that.