Better than that ------buy a memory extension that plugs into a usb
port --keep all your files etc on it .
Wanna use laptop --plug in your memory and use. Finished with laptop
remove your memory and keep it handy .[ Usually hanging around my neck on a string!!]
All new files store on the memory extension.
Laptop is then only for operating system requirements .
Thinking about it more seriously, if you use a magic stick as advised, I think that if thelaptop is stolen it might still be possible for someone who thought it was worthwhile to recover some or all of any data used from the hard disc from the working copy, unless you have the means to write random noughts and ones all over the disc area used by temporary datasets. Depends on the applications package and what you are doing with it. However, you do insulate yourself from losing your prime set of data.