1. Computer cases (most I've seen) have the way to use a lock..
2. Any strong password can be hacked but it takes a long time to achieve it with special software (and honestly, who would want to wait for months) so those Windows login passwords you have broken may have not been strong enough...
3. And if your information is on Office files you can add strong file passwords and use other passwords to protect each page after you insert a Word document into a xls Worksheet, hide the text, and another password to protect a xls/xlsx book, store them in ZIP/RAR or other compressed folders under password, in hidden locked and protected partitions or USB hard drive, flash drive, CD, DVD or Blu-Ray disk, etc.
You didn't mention partition locking software... did you break that to?
4. Disk or partition protection software use encryption and as far as I know, encryption can't be broken or at least without expensive software and after a long process.
Why so long to break 128-bit encryption?
http://security.stackexchange.com/questions/31726/why-so-long-to-break-128-bit-encryption
The disadvantage is you have to make sure you don't loose/forget the password and use a HDD that's in perfect condition because the encryption can make it impossible to recover from another Windows installation, computer or the web.
Encryption today: how safe is it really?
http://theconversation.com/encryption-today-how-safe-is-it-really-37806
5. And to make absolutely sure no one will hack your information, why not back it up in removable media that you can keep under lock, carry with you, save in a bank safe deposit box... if it's very important to you or valuable, that would be the best way to protect it and keep from stealing.